NAYLER, WINIFRED G., P. DAILE, DENISE CHIPPERFIELD, AND AND K. GAN. E&t of ryanodine on calcium in cardiac muscle. Am. j. Physiol. 219(6): 1620-1626. 1970.-The negative inotropic effect of ryanodine on mammalian heart muscle is accompanied by highly significant changes in time taken during contraction for peak tension to develop. Relaxation is slowed. Influx of 45ca remains unchanged and 4Qa ef...

Background: There are controversial reports about the exact mechanisms of lead-induced hypertension, but many factors such as alteration in the responsiveness of cardiovascular system to endogenous substances including catecholamines could be one of the mechanisms involved. In present study, the effect of exposure to 100 ppm lead acetate by drinking water (in the periods of 4, 8 and 12 weeks)...

Recent data from our laboratory suggest that sex steroids promote contractile function in cardiac muscle of rainbow trout (Oncorhynchus mykiss Walbaum), and there are sex differences in hormone signaling and cardiac function. The current study investigated whether steroid-induced inotropism in electrically paced (0.5 Hz, 14 degrees C) ventricle strips at 90% Lmax (1) has a metabolic requirement...

beta-Adrenergic signalling mediates the positive inotropic effect of catecholamines on cardiomyocytes, mainly through cAMP generation and subsequent activation of PKA (protein kinase A). Given the large diversity of PKA targets within cardiac cells, a precisely regulated and confined activity of such signalling pathways is essential for the specificity of response. PDEs (phosphodiesterases) con...

In an attempt to search for more potent positive inotropic agents, two series of [1,2,4]triazolo[4,3-a] quinoxaline derivatives bearing substituted benzylpiperazine and benzoylpiperazine moieties were synthesized and their positive inotropic activities evaluated by measuring left atrial stroke volume in isolated rabbit heart preparations. Several compounds showed favorable activities compared w...

Inotropic drugs are part of the treatment of heart failure; however, inotropic treatment has been largely debated due to the increased incidence of adverse effects and increased mortality. Recently levosimendan, an inotropic positive agent, has been proved to be effective in acute heart failure, reducing the mortality and improving cardiac and renal performance. We report the case of a 75-year-...