ABSTRACT
The effect of bradykinin (BK) on myocardial inotropic state was tested on 5 isolated rat heart preparations, in which a proper ballon was placed to record left ventricular pressure, whose developed systolic value was taken as an index of contractility. A reduction of developed left ventricular pressure was observed when BK was added to the perfusion oxygenated Tyrode solution. However, when BK was given after 1-amino-benzotriazole, an inhibitor of Cytochrome P-450 (Cyt P-450), developed pressure did not change. Since Cyt P-450 is known to act on arachidonic acid inducing the production of epoxiecocistrienoic acids (EETs) which hyperpolarizes myocardial fibres, it was argued that the reduction in contractility by bradykinin was the result of the hyperpolarizing effect of EETs. The fact that the concentration of Cyt P-450 is higher in the vascular endothelial cells than in the sarcolemma of the myocytes and the observation that the coronary resistance decreases together with the contractility suggest that the endothelium plays a pivotal role in mediating the negative inotropic effect of BK.
Subject(s)
Coronary Vessels/physiology , Myocardial Contraction/physiology , Vasodilation/physiology , Ventricular Function , Animals , Bradykinin/pharmacology , Coronary Vessels/drug effects , Coronary Vessels/enzymology , Cytochrome P-450 Enzyme Inhibitors , Cytochrome P-450 Enzyme System/metabolism , Endothelium, Vascular/drug effects , Endothelium, Vascular/physiology , Enzyme Activation/drug effects , Enzyme Inhibitors/pharmacology , Heart Ventricles/drug effects , In Vitro Techniques , Myocardial Contraction/drug effects , Perfusion , Rats , Rats, Wistar , Triazoles/pharmacology , Vasodilation/drug effects , Ventricular Function, Left/drug effects , Ventricular Function, Left/physiology , Ventricular Pressure/drug effects , Ventricular Pressure/physiologyABSTRACT
Following a brief analysis of the problem of hospital infections, the results of a review of 312 antibiograms carried out in the General Medicine Division of Cuneo's S. Croce Hospital in 1979 are reported.
