Aim: To evaluate the effects of beta3-adrenergic receptors (ARs) agonist (BRL-37344) on beating rate and cAMP levels and investigate the influence on the chronotropic action of beta3-ARs in cultured cardiomyocyte of rats.
Methods: Cultured neonatal rat cardiomyocytes were divided randomly into eight groups, control group, ISO group, Nadolol + ISO group, BRL group, PIX + BRL group, L-NAME + BRL group, Nadolol + BRL group and Bupranolol + BRL group. Beating rate of culture neonatal rat cardiomyocytes was observed and cAMP measured by enzyme immunoassay kit. Expression levels of beta3-ARs mRNA in cardiomyocytes was evaluated by reverse transcription-polymerase chain reaction (RT-PCR).
Results: ISO, nonspecific beta-ARs agonist increased beating rate and intracellular cAMP production, antagonized by Nadolol, beta1, beta2-ARs antagonist. BRL37344 decreased beating rate and intracellular cAMP levels. FPTX, Gi protein inhibitor and Bupranolol, nonspecific beta-ARs antagonist totally blocked the effect and L-NAME, nitric oxide synthase (NOS) inhibitor partly blocked the effect, but Nadolol did not. There was the expression of beta3-AR mRNA in cardiomyocytes by RT-PCR.
Conclusions: Beta3-ARs showed in cardiomyocytes and produced negative chronotropic effects. beta1, beta2-ARs antagonist did not affect it. It suggested beta3-ARs signal transduction was related with G1 protein. The negative inotropic effect of beta3-ARs stimulation was mediated by activation of the NOS pathway.
University of California, Division of Pulmonary, Critical Care, Sleep Medicine and Physiology, 9300 Campus Point Drive, MC #7381, La Jolla, San Diego, CA 92037. Electronic address:
Unlabelled: Exercise-induced pulmonary arterial hypertension (EiPH) is often treated with off-label use of pulmonary arterial hypertension-targeted therapy (PH-targeted therapy). Most measures of PAH severity are normal in patients with EiPH, posing challenges in evaluating for physiological improvement in patients treated for EiPH. In this study, we used non-invasive cardiopulmonary exercise testing (CPET) to assess for objective improvement in patients treated for EiPH.
Cardiotoxicity associated with hepatic metabolism and drug-drug interactions is a serious concern. Predicting drug toxicity using animals remains challenging due to species and ethical concerns, necessitating the need to develop alternative approaches. Drug cardiotoxicity associated with hepatic metabolism cannot be detected using a cardiomyocyte-only evaluation system.
Division of Pulmonary, Critical Care, and Sleep Medicine, College of Medicine-Jacksonville, University of Florida, 653-1 West 8th Street, L20 Jacksonville, FL 32209, USA.
Electronic cigarette (EC) is widely advertised as a safe alternative to traditional cigarette (TC). We aimed to investigate the cardiovascular effect of EC with/without nicotine compared with TC. We systematically searched PubMed/MEDLINE, EMBASE, and Cochrane CENTRAL for randomized controlled trials that compared the effect of different smoking modalities on cardiovascular function up to 1 October 2024.
We describe a case of profound bradyarrhythmia after sugammadex administration during ambulatory anesthesia. The patient was a 21-year-old man with autism spectrum disorder undergoing planned general anesthesia for dental treatment. After treatment completion, sugammadex was administered upon awakening, and sudden bradyarrhythmia appeared immediately.
The effect of a citrus-derived flavonoid, hesperetin, on the automaticity and contraction of isolated guinea pig myocardium was examined. Hesperetin inhibited the rate of ectopic action potential firing of the pulmonary vein myocardium; the slope of the diastolic depolarization was decreased with minimum change in the action potential waveform. The effect was dependent on the concentration; the EC value for firing rate was 56.
