Effect of FR 7534, a new calcium antagonist, on myocardial oxygen demand

Plasma membrane fluidity studies by fluorescence polarization in rat mast cells stimulated by compound 48/80

Plasma membrane fluidity measurements were performed on purified living mast cells using a novel non-permeant fluorescence polarization probe TMA-DPH, upon stimulation by compound 48/80. The fluorescence anisotropy increased rapidly after treatment by 48/80 in a dose-dependent way. The effect was found to be specific for mast cells; it was inhibited by the histamine release antagonist FR 7534 in a correlative manner. The role of calcium was examined. The results brought evidence for a plasma membrane fluidity decrease induced by 48/80; a biphasic mechanism was inferred for the histamine release process.

Comparative effects of FR 34235, a new slow channel calcium blocker, and nifedipine on hemodynamics and myocardial oxygen consumption in the anesthetized dog

Five doses of two dihydropyridine calcium antagonists, FR 34235 and nifedipine, were given intravenously to anesthetized dogs to determine effects on hemodynamics and myocardial oxygen balance. Both agents produced dose-related decreases in mean arterial blood pressure and tension time index with little effect on heart rate, dP/dt or myocardial contractile force except at high doses where small decreases were observed. Coronary blood flow increased markedly in the presence of both agents with a maximum increase observed at doses of 10 and 30 micrograms/kg for FR 34235 and nifedipine, respectively. Both compounds decreased myocardial oxygen extraction at all doses and reduced myocardial oxygen consumption at higher doses. These results indicate that FR 34235, a new slow channel calcium blocker, is a potent coronary vasodilator. In addition, this compound possesses oxygen-sparing activity at higher doses.