Norepinephrine and isoprenaline induced changes of peripheral blood flow acceleration caused by changes of cardiac inotropy.

In anesthetized dogs the norepinephrine (NE) and isoprenaline (ISO) (1--1024 ng/kg i.v.)--induced increase of maximum peripheral flow acceleration (celiac artery, cranial mesenteric artery, renal artery; and femoral artery) and the changes of the maximum first derivative of arterial pressure were compared with the increases of maximum ascending aortic flow acceleration and maximum first derivative of left ventricle pressure (LV dP/dt max). The maximum effect of each dose on maximum acceleration of flows (dF/dt max) and maximum first derivative of pressures (dP/dt max) occurred simultaneously for all v56--512 ng/kg) and for ISO (D50:128--256) ng/kg). We demonstrated that other varure) played only a minor role in the increases of LV dP/dt max in our studies. In contrast with the uniform response of dF/dt max and dP/dt max, the reaction of peripheral vascular resistance varied. In particular in the gastrointestinal tract the resistance could either be increased (NE, D50:115 ng/kg) or decreases (ISO, D50:15 ng/kg). Gastrointestinal resistance was a more sensitive variable for catecholamine stimulation than dF/dt max and dP/dt max. The data show that under the present experimental conditions induced by NE and ISO is due to increase of cardiac inotropy.