Comparison of alpha-MSH and several vasoactive substances on vascular resistance in the feline mesenteric vascular bed.

The effects of alpha-MSH and several other vasoactive substances on the mesenteric vascular bed were studied in the anesthetized cat under conditions of controlled blood flow. Intra-arterial injections of alpha-MSH in doses of 10, 30, and 100 mug resulted in significant dose-related decreases in mesenteric arterial perfusion pressure but little or no effect on systemic arterial pressure. The vasodilator response to alpha-MSH was breif in duration and resistance to flow was decreased 10, 18, and 26 percent at 10, 30, and 100 mug. These significant changes after alpha-MSH were of a much smaller magnitude than were observed after prostaglandins E1 and E2, isoproterenol, bradykinin or glyceryl trinitrate and differed completely from the increased resistance after angiotensin II and norepinephrine.