Distribution of the increased cardiac output secondary to the vasodilating and inotropic effects of secretin.

Infusion of the peptide secretin augments cardiac output due to vasodilating and inotropic properties. The aim of this investigation was to study how the increased cardiac output is distributed in the peripheral circulation. Before, during and after 15 min infusion of secretin 64 CU kg-1 h-1 flow changes in renal, carotid, femoral and the superior mesenteric arteries were measured by means of electromagnetic flowmetry in anaesthetized dogs. Cardiac output and stroke volume increased by 41 and 27%, respectively, whereas the total systemic resistance fell 35%. The LVdP/dt increased by 35%. After 5 min infusion, renal and carotid flows increased by 62 and 50%, respectively, whereas the femoral flow was only slightly elevated and the superior mesenteric flow unchanged. Both the femoral and the superior mesenteric flow gradually augmented and at the end of the infusion flow was substantially elevated in all four arteries. The study demonstrated that the increased cardiac output by secretin was distributed to all the four arteries, although a preponderance of flow to the renal circulation was indicated. This flow profile may be regarded as favourable in the management of low output conditions.