Contractile Activity of Arterioles in the Bat Wing during Intraluminal Pressure Changes

Abstract

Spontaneous contractile activity in the smooth muscle cells that invest arteriolar vessels is widely variable. Arteriolar branches originating from the same parent vessel contract independently of one another with no similarity in frequency or duration of individual contractions. Direct microscopic observations were made of these vessels in the wing of unanesthetized bats before and after surgical denervation or nerve block by procaine. A major artery of the wing was cannulated and buffered saline was perfused in retrograde fashion to produce periods of increased intra-arterial pressure. Elevation of intraluminal pressure led to enhanced contractile activity both before and after denervation of the vessels. It is concluded that these vessels respond by contraction to increased pressure and that the response is not dependent on nervous activity.