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Updated: Aug 2, 2026
En Face Detection of Nitric Oxide and Superoxide in Endothelial Layer of Intact Arteries
Published on: February 25, 2016
[Regulation of cardiac functions by the L-arginine--nitric oxide system]
Insights
Intracoronary L-arginine and sodium nitroprusside increase coronary flow, myocardial contractility, and heart rate in isolated rat hearts. L-arginine primarily boosts coronary flow, which secondarily enhances contractility.
Area of Science:
- Cardiovascular Physiology
- Pharmacology
Context:
- Investigating the effects of vasoactive substances on cardiac function.
- Utilizing an isolated perfused rat heart model to control variables.
Purpose:
- To determine the effects of L-arginine and sodium nitroprusside on coronary flow (CF), myocardial contractility (MC), and heart rate (HR).
- To elucidate the mechanisms underlying these observed physiological changes.
Summary:
- Intracoronary infusion of L-arginine and sodium nitroprusside elicited increases in CF, MC, and HR in isolated rat hearts.
- L-arginine predominantly increased CF, with secondary enhancement of MC (Gregg's phenomenon).
- Sodium nitroprusside's positive inotropic effect stemmed mainly from direct myocardial action, with a minor contribution from increased CF.
Impact:
- Provides mechanistic insights into the cardiovascular actions of L-arginine and sodium nitroprusside.
- Highlights the interplay between coronary blood flow and myocardial contractility.
- Informs potential therapeutic strategies targeting coronary circulation and cardiac performance.
Abstract:
It is shown that intracoronary infusion of L-arginine and sodium nitroprusside induces an increase in coronary flow (CF), myocardial contractility (MC) and heart rate (HR) in the isolated perfused heart of the rat. Three combinations of these effects have been observed in different experiments: generalized effect (increase of CF + MC + HR), a double effect in three variants (increase of CF + MC, CF + HR, MC + HR) and isolated effect (increase of CF or MC or HR). The data obtained suggest that an increase of CF is the main change induced by L-arginine in the isolated perfused heart, an increase of MC being secondary in relation to a CF increase, i.e. an increase of CF mediates an increase of MC (Gregg's phenomenon). A positive inotropic effect of sodium nitroprusside is the result mainly of its direct action on the myocardium and to a lesser extent due to a CF increase.
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