[The effect of intravenous infusion of glucagon on the contractility of the left ventricular myocardum in man (author's transl)].

In the cases of 10 cardially healthy humans and 5 patients with heart disease, the left ventricular pressure as well as different parameters of contractility - deduced from the pressure curve and its first derivative - were determined by a catheter-tip manometer (Statham SF - 1). In particular the following values were concerned: dP/dtmax,-dP/dtmaxDP, the maximal calculated shortening velocity of the contractile elements according to the 2-component heart muscle model (VCEmaxTP) as well as with the Maxwell model (VCEmaxDP) and finally the (extrapolated) maximum shortening velocity (Vmax) under a fictive zero load. The examinations were carried out before and during a 10-minute infusion of 60 mg/kg glucagon and 10 minutes after completing the infusion. Besides glucagon also digoxin, etilefrin-HCl-1) and orciprenaline-2) were delivered and the same measurements were performed as with glucagon. A definite statement about the priority of any one of the named indices of contractility is rendered more difficult, because the enddiastolic pressure does not change substantially with glucagon. An unequivocal demarcation of frequency and pressure effects and of inotropic mechanisms as just as impossible, because, with the exception of VmaxDP, all parameters react quantitatively and qualitatively in an equal manner. On the basis of VmaxTP the result of glucagon is only a slight increase in the myocardial contractile capability, which would hardley suffice for the treatment of patients, who do not respond to digitalis. The decline of VmaxDP under glucagon cannot be explained. Under digitalis, etilefrin and orciprenaline, a similar dissociation of values for the maximum shortening velocity according to the 2- or 3-component-model of the heart muscle cannot be demonstrated.