Inotropic and chronotropic effect of glycerol formal on the isolated rabbit heart

Glycerol formal (CAS 5464-28-8), an organic solvent used to vehicle drugs to target cells, has been shown to possess its own toxicopharmacological properties. The present work was undertaken to study its direct effect on the isolated rabbit heart. At 2.3 and 4.6 mmol/l (bolus) glycerol formal exerted a positive inotropic effect. Upon a perfusion of 4.5 mmol/l/h, the left ventricular pressure and the coronary flow were increased, while at 11 mmol/l/h these two parameters showed a tendency to decrease. Glycerol formal upon a perfusion at 11 mmol/l/h decreased mildly the positive inotropic effect of noradrenaline, and strongly that produced by acetylcholine at a nicotinic dose, while it accentuated the bradycardia induced by acetylcholine at a muscarinic dose. On the contrary it potentiated the stimulant effect of nicotine. The positive inotropic effects of tyramine, dimethylphenylpiperazinium and potassium chloride were decreased showing an inhibition of noradrenaline liberation induced by glycerol formal at the doses used. The action of glycerol formal on agents inducing a positive inotropic effect, except nicotine, and its cardiodepressant effect are probably partly due to its action on the Ca2+ ion.