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The Journal of Pharmacology and... Jun 2024Streptolysin O (SLO), a bacterial toxin produced by common hemolytic streptococci, including and resident microbiota, may be associated with inflammation in the...
Streptolysin O (SLO), a bacterial toxin produced by common hemolytic streptococci, including and resident microbiota, may be associated with inflammation in the cardiovascular system. We previously reported that short-term treatment with SLO at relatively high concentrations (10-1000 ng/mL) diminished acetylcholine-induced, endothelial-dependent relaxation in a concentration-dependent manner. However, the vascular function effects of long-term exposure to SLO at lower concentrations are poorly understood. In this study, treatment of rat aorta with endothelium with SLO (0.1-10 ng/mL) for 72 h inhibited contractions in response to norepinephrine and phenylephrine in a concentration-dependent manner, and this effect was abolished by endothelium denudation. We also observed decreased endothelium-dependent relaxation in aorta treated with a lower concentration of SLO (10 ng/mL) for 72 h. Long-term treatment with SLO (10 ng/mL) increased the expression of iNOS in aorta with endothelium but not aorta without endothelium, and the SLO-induced decrease in contraction was restored by treatment with NOS inhibitors. Pharmacologic and gene-mutant analyses further indicated that SLO-induced vascular dysfunction and iNOS upregulation are mediated through the TLR4/NOX2/ROS/p38 MAPK pathways. SLO treatment (46.8 pg/kg/min) for 7 days also diminished vascular contraction and relaxation activity in aorta with endothelium. We concluded that long-term treatment with SLO inhibits vascular contractile responses, primarily due to increased iNOS expression in the endothelium through TLR4-mediated pathways. Our present results, together with those of our previous study, suggest that endothelial cells play a key role in the pathophysiologic changes in cardiovascular function associated with long-term exposure to SLO. In the present study, we showed that long-term exposure to streptococcal exotoxin SLO inhibits agonist-induced contraction in rat aorta with endothelium, driven primarily by elevated iNOS production via NOX2-mediated ROS production through TLR4 activation on endothelial cells. treatment with SLO for 7 days also diminished vascular contraction and relaxation, providing evidence of possible pathophysiologic roles of SLO in endothelium-dependent vascular homeostasis.
PubMed: 38858090
DOI: 10.1124/jpet.124.002121 -
The Journal of Physiology Jun 2024Heart failure with preserved ejection fraction (HFpEF) has been characterized by lower blood flow to exercising limbs and lower peak oxygen utilization ( ), possibly...
Heart failure with preserved ejection fraction (HFpEF) has been characterized by lower blood flow to exercising limbs and lower peak oxygen utilization ( ), possibly associated with disease-related changes in sympathetic (α-adrenergic) signaling. Thus, in seven patients with HFpEF (70 ± 6 years, 3 female/4 male) and seven controls (CON) (66 ± 3 years, 3 female/4 male), we examined changes (%Δ) in leg blood flow (LBF, Doppler ultrasound) and leg to intra-arterial infusion of phentolamine (PHEN, α-adrenergic antagonist) or phenylephrine (PE, α-adrenergic agonist) at rest and during single-leg knee-extension exercise (0, 5 and 10 W). At rest, the PHEN-induced increase in LBF was not different between groups, but PE-induced reductions in LBF were lower in HFpEF (-16% ± 4% vs. -26% ± 5%, HFpEF vs. CON; P < 0.05). During exercise, the PHEN-induced increase in LBF was greater in HFpEF at 10 W (16% ± 8% vs. 8% ± 5%; P < 0.05). PHEN increased leg in HFpEF (10% ± 3%, 11% ± 6%, 15% ± 7% at 0, 5 and 10 W; P < 0.05) but not in controls (-1% ± 9%, -4% ± 2%, -1% ± 5%; P = 0.24). The 'magnitude of sympatholysis' (PE-induced %Δ LBF at rest - PE-induced %Δ LBF during exercise) was lower in patients with HFpEF (-6% ± 4%, -6% ± 6%, -7% ± 5% vs. -13% ± 6%, -17% ± 5%, -20% ± 5% at 0, 5 and 10 W; P < 0.05) and was positively related to LBF, leg oxygen delivery, leg , and the PHEN-induced increase in LBF (P < 0.05). Together, these data indicate that excessive α-adrenergic vasoconstriction restrains blood flow and limits of the exercising leg in patients with HFpEF, and is related to impaired functional sympatholysis in this patient group. KEY POINTS: Sympathetic (α-adrenergic)-mediated vasoconstriction is exaggerated during exercise in patients with heart failure with preserved ejection fraction (HFpEF), which may contribute to limitations of blood flow, oxygen delivery and oxygen utilization in the exercising muscle. The ability to adequately attenuate α-adrenergic vasoconstriction (i.e. functional sympatholysis) within the vasculature of the exercising muscle is impaired in patients with HFpEF. These observations extend our current understanding of HFpEF pathophysiology by implicating excessive α-adrenergic restraint and impaired functional sympatholysis as important contributors to disease-related impairments in exercising muscle blood flow and oxygen utilization in these patients.
PubMed: 38843407
DOI: 10.1113/JP285526 -
Open Medicine (Warsaw, Poland) 2024Understanding the intricate relationship between cancer clinicopathological features and anesthetics dosage is crucial for optimizing patient outcomes and safety during...
Understanding the intricate relationship between cancer clinicopathological features and anesthetics dosage is crucial for optimizing patient outcomes and safety during surgery. This retrospective study investigates this relationship in patients with non-small cell lung cancer (NSCLC) undergoing video-assisted thoracic surgery (VATS). A comprehensive analysis of medical records was undertaken for NSCLC patients who underwent VATS with intravenous compound inhalation general anesthesia. Patients were categorized based on histological, chemotherapy, radiotherapy, and epidural anesthesia factors. Statistical analysis was performed to compare the differences between the groups. The results revealed compelling insights. Specifically, patients with lung adenocarcinoma (LUAD) undergoing VATS exhibited higher dosages of rocuronium bromide and midazolam during general anesthesia, coupled with a shorter post-anesthesia care unit (PACU) stay compared to those with squamous cell carcinoma (sqCL). Furthermore, chemotherapy patients undergoing VATS demonstrated diminished requirements for phenylephrine and remifentanil in contrast to their non-chemotherapy counterparts. Similarly, radiotherapy patients undergoing VATS demonstrated a decreased necessity for rocuronium bromide compared to non-radiotherapy patients. Notably, patients who received epidural anesthesia in combination with general anesthesia manifested reduced hydromorphone requirements and prolonged hospital stays compared to those subjected to general anesthesia alone. In conclusion, the findings from this study indicate several important observations in diverse patient groups undergoing VATS. The higher dosages of rocuronium bromide and midazolam in LUAD patients point to potential differences in drug requirements among varying lung cancer types. Additionally, the observed shorter PACU stay in LUAD patients suggests a potentially expedited recovery process. The reduced anesthetic requirements of phenylephrine and remifentanilin chemotherapy patients indicate distinct responses to anesthesia and pain management. Radiotherapy patients requiring lower doses of rocuronium bromide imply a potential impact of prior radiotherapy on muscle relaxation. Finally, the combination of epidural anesthesia with general anesthesia resulted in reduced hydromorphone requirements and longer hospital stays, suggesting the potential benefits of this combined approach in terms of pain management and postoperative recovery. These findings highlight the importance of tailoring anesthesia strategies for specific patient populations to optimize outcomes in VATS procedures.
PubMed: 38841176
DOI: 10.1515/med-2024-0961 -
The Journal of Biological Chemistry Jun 2024During postnatal cardiac hypertrophy, cardiomyocytes undergo mitotic exit, relying on DNA replication-independent mechanisms of histone turnover to maintain chromatin...
During postnatal cardiac hypertrophy, cardiomyocytes undergo mitotic exit, relying on DNA replication-independent mechanisms of histone turnover to maintain chromatin organization and gene transcription. In other tissues, circadian oscillations in nucleosome occupancy influence clock-controlled gene expression, suggesting a role for the circadian clock in temporal control of histone turnover and coordinated cardiomyocyte gene expression. We sought to elucidate roles for the master circadian transcription factor, Bmal1, in histone turnover, chromatin organization, and myocyte-specific gene expression and cell growth in the neonatal period. Bmal1 knockdown in neonatal rat ventricular myocytes decreased myocyte size, total cellular protein synthesis, and transcription of the fetal hypertrophic gene Nppb after treatment with serum or the α-adrenergic agonist phenylephrine. Depletion of Bmal1 decreased the expression of clock-controlled genes Per2 and Tcap, as well as Sik1, a Bmal1 target upregulated in adult versus embryonic hearts. Bmal1 knockdown impaired Per2 and Sik1 promoter accessibility as measured by micrococcal nuclease-quantitative PCR and impaired histone turnover as measured by metabolic labeling of acid-soluble chromatin fractions. Sik1 knockdown in turn decreased myocyte size, while simultaneously inhibiting natriuretic peptide B transcription and activating Per2 transcription. Linking these changes to chromatin remodeling, depletion of the replication-independent histone variant H3.3a inhibited myocyte hypertrophy and prevented phenylephrine-induced changes in clock-controlled gene transcription. Bmal1 is required for neonatal myocyte growth, replication-independent histone turnover, and chromatin organization at the Sik1 promoter. Sik1 represents a novel clock-controlled gene that coordinates myocyte growth with hypertrophic and clock-controlled gene transcription. Replication-independent histone turnover is required for transcriptional remodeling of clock-controlled genes in cardiac myocytes in response to growth stimuli.
PubMed: 38830405
DOI: 10.1016/j.jbc.2024.107434 -
Journal of Cerebral Blood Flow and... May 2024This study measured the relationship between pial collateral (leptomeningeal anastomoses, LMA) flow, intraparenchymal cortical cerebral blood flow (cCBF) and brain...
This study measured the relationship between pial collateral (leptomeningeal anastomoses, LMA) flow, intraparenchymal cortical cerebral blood flow (cCBF) and brain tissue oxygenation (btO) during acute ischemic stroke to investigate how pial flow translates to downstream cCBF and btO and examined how this relationship is altered in hypertension. Proximal transient middle cerebral artery occlusion (tMCAO) was performed in male Wistar (n = 8/group) and Spontaneously Hypertensive Rats (SHR, n = 8/group). A combination laser Doppler-oxygen probe was placed within the expected cortical peri-infarct in addition to a surface laser doppler probe which measured LMA flow. Phenylephrine (PE) was infused 30 minutes into tMCAO to increase blood pressure (BP) by 30% for 10 minutes and assessed CBF autoregulation. During the initial 30-minute period of tMCAO, btO and cCBF were lower in SHR compared to Wistar rats (btO: 11.5 ± 10.5 vs 17.5 ± 10.8 mmHg and cCBF: -29.7 ± 23.3% vs -17.8 ± 41.9%); however, LMA flow was similar between groups. The relationship between LMA flow, cCBF and btO were interdependent in Wistar rats. However, this relationship was disrupted in SHR rats and partially restored by induced hypertension. This study provides evidence that cCBF and btO were diminished during tMCAO in chronic hypertension, and that induced hypertension was beneficial regardless of hypertensive status.
PubMed: 38806143
DOI: 10.1177/0271678X241258569 -
Journal of Anesthesia May 2024The hemodynamic effects of relatively low-dose epinephrine and phenylephrine infusions during cesarean delivery under spinal anesthesia were compared.
BACKGROUND
The hemodynamic effects of relatively low-dose epinephrine and phenylephrine infusions during cesarean delivery under spinal anesthesia were compared.
METHODS
This randomized controlled trial included full-term pregnant women who underwent elective cesarean delivery. After spinal anesthesia, participants received either epinephrine (0.03 mcg/kg/min) or phenylephrine (0.4 mcg/kg/min) infusion that continued until 5 min after delivery. The primary outcome was a composite outcome of the occurrence of any of hypotension, hypertension, bradycardia, and/or tachycardia. Neonatal outcomes, including umbilical artery blood gas and Apgar scores, were assessed.
RESULTS
In total, 98 patients in each group were analyzed, and the number of patients with the composite outcome was comparable between the epinephrine and phenylephrine groups (30/98 [31%] vs. 31/98 [32%], respectively; P = 0.877). However, the incidence of hypotension was likely lower in the epinephrine group than in the phenylephrine group (P = 0.066), and the number of hypotensive episodes per patient was lower in the epinephrine group than in the phenylephrine group. On the other hand, the incidence of tachycardia was higher in the epinephrine group than that in the phenylephrine group. The incidence of hypertension was comparable between the two groups and none of the participants developed bradycardia. Neonatal outcomes were comparable between the two groups.
CONCLUSIONS
Epinephrine and phenylephrine infusion produced comparable maternal hemodynamics and neonatal outcomes. Epinephrine was associated with a higher incidence of maternal tachycardia and likely lower incidence of maternal hypotension than phenylephrine. IRB number: MD-245-2022.
CLINICAL TRIAL REGISTRATION
This study was registered on May 31, 2023 at clinicaltrials.gov registry, NCT05881915, URL: https://classic.
CLINICALTRIALS
gov/ct2/show/NCT05881915term=NCT05881915&draw=2&rank=1.
PubMed: 38789602
DOI: 10.1007/s00540-024-03344-2 -
Brazilian Journal of Medical and... 2024Arthritis has important cardiovascular repercussions. Phenylephrine-induced vasoconstriction is impaired in rat aortas in the early phase of the adjuvant-induced...
Arthritis has important cardiovascular repercussions. Phenylephrine-induced vasoconstriction is impaired in rat aortas in the early phase of the adjuvant-induced arthritis (AIA), around the 15th day post-induction. Therefore, the present study aimed to verify the effects of AIA on hyporesponsiveness to phenylephrine in rat aortas. AIA was induced by intradermal injection of Mycobacterium tuberculosis (3.8 mg/dL) in the right hind paw of male Wistar rats (n=27). Functional experiments in isolated aortas were carried out 15 days after AIA induction. Morphometric and stereological analyses of the aortas were also performed 36 days after the induction of AIA. AIA did not promote structural modifications in the aortas at any of the time points studied. AIA reduced phenylephrine-induced contraction in endothelium-intact aortas, but not in endothelium-denuded aortas. However, AIA did not change KCl-induced contraction in either endothelium-intact or denuded aortas. L-NAME (non-selective NOS inhibitor), 1400W (selective iNOS inhibitor), and ODQ (guanylyl cyclase inhibitor) reversed AIA-induced hyporesponsiveness to phenylephrine in intact aortas. 7-NI (selective nNOS inhibitor) increased the contraction induced by phenylephrine in aortas from AIA rats. In summary, the hyporesponsiveness to phenylephrine induced by AIA was endothelium-dependent and mediated by iNOS-derived NO through activation of the NO-guanylyl cyclase pathway.
Topics: Animals; Male; Phenylephrine; Rats, Wistar; Arthritis, Experimental; Nitric Oxide; Vasoconstriction; Endothelium, Vascular; Vasoconstrictor Agents; Rats; Aorta
PubMed: 38775546
DOI: 10.1590/1414-431X2024e13304 -
Pharmaceutical Biology Dec 2024The mechanisms of Traditional Chinese Medicine (TCM) Guizhi-Gancao Decoction (GGD) remain unknown.
Network pharmacology integrated with experimental validation to elucidate the mechanisms of action of the Guizhi-Gancao Decoction in the treatment of phenylephrine-induced cardiac hypertrophy.
CONTEXT
The mechanisms of Traditional Chinese Medicine (TCM) Guizhi-Gancao Decoction (GGD) remain unknown.
OBJECTIVE
This study explores the mechanisms of GGD against cardiac hypertrophy.
MATERIALS AND METHODS
Network pharmacology analysis was carried out to identify the potential targets of GGD. experiments, C57BL/6J mice were divided into Con, phenylephrine (PE, 10 mg/kg/d), 2-chloroadenosine (CADO, the stable analogue of adenosine, 2 mg/kg/d), GGD (5.4 g/kg/d) and GGD (5.4 g/kg/d) + CGS15943 (a nonselective adenosine receptor antagonist, 4 mg/kg/d). experiments, primary neonatal rat cardiomyocytes (NRCM) were divided into Con, PE (100 µM), CADO (5 µM), GGD (10 g/mL) and GGD (10 g/mL) + CGS15943 (5 µM). Ultrasound, H&E and Masson staining, hypertrophic genes expression and cell surface area were conducted to verify the GGD efficacy. Adenosine receptors (ADORs) expression were tested real-time polymerase chain reaction (PCR), western blotting and immunofluorescence analysis.
RESULTS
Network pharmacology identified ADORs among those of the core targets of GGD. experiments demonstrated that GGD attenuated PE-induced increased surface area (with an EC of 5.484 × 10 g/mL). data shown that GGD attenuated PE-induced ventricular wall thickening. and data indicated that GGD alleviated PE-induced hypertrophic gene expression (e.g., ANP, BNP and MYH7/MYH6), A1AR over-expression and A2aAR down-expression. Moreover, CADO exerts effects similar to GGD, whereas CGS15943 eliminated most effects of GGD.
DISCUSSION AND CONCLUSIONS
Our findings suggest the mechanism by which GGD inhibits cardiac hypertrophy, highlighting regulation of ADORs as a potential therapeutic strategy for HF.
Topics: Animals; Drugs, Chinese Herbal; Phenylephrine; Cardiomegaly; Mice, Inbred C57BL; Mice; Male; Rats; Myocytes, Cardiac; Network Pharmacology; Rats, Sprague-Dawley; Cells, Cultured; Disease Models, Animal; Medicine, Chinese Traditional
PubMed: 38773737
DOI: 10.1080/13880209.2024.2354335 -
Ophthalmic Plastic and Reconstructive... May 2024This study aims to evaluate the influence of preoperative phenylephrine testing on the surgical outcome of patients undergoing surgery for involutional ptosis by...
PURPOSE
This study aims to evaluate the influence of preoperative phenylephrine testing on the surgical outcome of patients undergoing surgery for involutional ptosis by external levator advancement.
METHODS
This was an observational, monocentric, retrospective study. Fifty-one eyelids from 32 patients, who had surgery between January 2018 and May 2023, were included for analysis. Preoperative clinical examination data were collected. Evaluation was performed at 1 month postoperatively. Surgical success was defined by a postoperative margin reflex distance between 3 and 5 mm inclusive. Symmetry success was defined by a difference in margin reflex distance between the 2 upper eyelids of no more than 1 mm.
RESULTS
The surgical success rate was 86%. A positive preoperative phenylephrine test was significantly associated with a better surgical success rate (p = 0.01), including on symmetry (p = 0.01). The secondary outcomes, namely preoperative margin reflex distance, function of the upper eyelid levator muscle, and unilaterality of surgery, were not statistically associated with surgical outcome.
CONCLUSIONS
The phenylephrine test is a predictive factor of surgical success in patients undergoing external levator advancement. Our study suggests that patients with a negative phenylephrine test should be overcorrected intraoperatively.
PubMed: 38771896
DOI: 10.1097/IOP.0000000000002675 -
Investigative Ophthalmology & Visual... May 2024Earlier reports highlighted the predominant presence of aquaporin 4 (AQP4) in the duct cells of rabbit lacrimal glands (LGs). Whereas significant alterations in AQP4...
PURPOSE
Earlier reports highlighted the predominant presence of aquaporin 4 (AQP4) in the duct cells of rabbit lacrimal glands (LGs). Whereas significant alterations in AQP4 mRNA levels have been observed in experimental dry eye and during pregnancy, the impact of AQP4 in LG ductal fluid production remains unclear. In our recent work, the role of AQP4 in LG ductal fluid secretion was investigated utilizing wild type (WT) and AQP4 knock out (KO) mice.
METHODS
Tear production was assessed in both WT and KO animals. Immunostaining was used to identify AQP4 protein. Duct segments were harvested from LGs of WT and KO mice. Fluid secretion and filtration permeability (Pf) were quantified using video-microscopy. Ductal tear production, elicited by a cell-permeable cAMP analogue (8-bromo cAMP), carbachol, vasoactive intestinal peptide (VIP), and phenylephrine (PHE), were assessed in both WT and KO ducts.
RESULTS
A higher expression of AQP4 protein was noted in the duct cells from WT mice when compared to acinar cells. Pf did not show notable alterations between WT and AQP4 KO ducts. Carbachol elicited comparable secretory responses in ducts from both WT and KO animals. However, 8-bromo cAMP, VIP, and PHE stimulation resulted in decreased secretion in ducts from AQP4 KO LGs.
CONCLUSIONS
Our findings underscore the functional relevance of AQP4 in the fluid production of mouse LG ducts. AQP4 seems to play different roles in fluid secretions elicited by different secretagogues. Specifically, cAMP-mediated, and adrenergic agonist-related secretions were reduced in AQP4 KO ducts.
Topics: Animals; Mice; Lacrimal Apparatus; Tears; Mice, Knockout; Aquaporin 4; Mice, Inbred C57BL; Female
PubMed: 38771571
DOI: 10.1167/iovs.65.5.30