PMID: 9190870Jun 1, 1997Paper

Acute effects of nitric oxide and cyclic GMP on human myocardial contractility

The Journal of Pharmacology and Experimental Therapeutics
M FleschM Böhm

Abstract

Evidence that the activity of nitric oxide synthase and the generation of nitric oxide (NO) within the myocardium are enhanced in several cardiovascular disorders is increasing. Findings whether NO exerts a direct effect on cardiac contractility are contradictory. Therefore, the direct effect of the NO donor sodium nitroprusside (SNP) on isometric force of contraction of human atrial and ventricular myocardium was investigated, and the question was addressed whether the effects of NO on cardiac contractility are mediated via cGMP. Experiments were performed on isolated electrically driven (1 Hz, 37 degrees C) human right atrial trabecula and left ventricular papillary muscle preparations from nonfailing and terminally failing hearts. SNP led to a concentration-dependent decrease of force of contraction (FOC) with a maximum effect at 100 micromol/l. In atrial trabecula, SNP (100 micromol/l) caused an acute decrease in basal FOC as well as in FOC after application of isoprenaline or IBMX by 12.5 +/- 5% (P < .05), 16.6 +/- 3.7% (P < .05) and 18.3 +/- 4.2% (P < .05), respectively. The negative inotropic effects could be attenuated by the guanylyl cyclase inhibitor methylene blue. In papillary muscle preparations, NO release caused ...Continue Reading

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