Intestinal muscle and mucosal blood flow during direct sympathetic stimulation.
The effect of direct sympathetic stimulation on intestinal muscle and submucosal-mucosal vasculatures was studied in the anesthetized rat. Blood flow was calculated from direct measurements of vessel diameter and red cell velocity. Stimulation at 4 Hz caused a slight reduction (4%) in muscle flow, but had no measurable effect on submucosal-mucosal flow; stimulation at 8 and 16 Hz caused muscle flow to decrease to 58.3 +/- 8.7% (SE) and 31 +/- 5.1%, respectively, of control flow, and mucosal flow, to 73 +/- 3.4% and 54.1 +/- 1.2%, respectively, of control flow. Calculations of muscle and mucosal vascular resistances from flows and microvascular pressures indicate that muscle resistance increased proportionately more than mucosal resistance at 4 and 8 Hz. However, during stimulation at 16 Hz, the mucosal resistance is only 55% of control, and muscle resistance is not significantly (P less than 0.05) different from control. Therefore, reduction of muscle and mucosal flows during 16-Hz stimulation must be caused by the intestinal arterioles and venules in series with these vasculatures.
D000818:Animals; D001794:Blood Pressure; D003714:Denervation; D004558:Electric Stimulation; D007413:Intestinal Mucosa / Q000098:blood supply*; D007421:Intestine, Small / Q000294:innervation; D007422:Intestines / Q000098:blood supply*; D008297:Male; D008833:Microcirculation; D009130:Muscle, Smooth / Q000098:blood supply; D051381:Rats; D012039:Regional Blood Flow; D013564:Sympathetic Nervous System / Q000502:physiology*; D014655:Vascular Resistance