AUTHORS' SYNOPSIS: The effects of severe, spontaneous exercise were studied on mesenteric and renal blood flows and resistances before and after splenectomy in six unrestrained, healthy dogs instrumented with miniature pressure gauges in the aorta and ultrasonic Doppler flow probes on the mesenteric and renal arteries. Before splenectomy, exercise increased haematocrit from 40 to 49%, heart rate from 76 to 290/min, mean arterial pressure from 93 to 134 mm Hg, mesenteric (+ 57%) and renal (+ 55%) resistances, while mesenteric and renal flows remained essentially constant. After splenectomy, exercise failed to increase haematocrit and increased vascular resistances to a far greater extent in the mesenteric (+144%) and renal (+199%) beds than in the intact dog, while reducing mesenteric flow by an average of 33% and renal flow by an average of 44%. Thus, in the dog the spleen contributes to the response to exercise by increasing haematocrit sufficiently to obviate reduction and diversion of visceral flows.
All Science Journal Classification (ASJC) codes
- Cardiology and Cardiovascular Medicine
- Physiology (medical)