Blood Flow through Terminal Arterial Vessels after Denervation of the Bat Wing

Abstract

Previous studies of microcirculation in the denervated wing of the unanesthetized bat showed that major arterial vessels increased markedly in diameter and lost their ability to contract spontaneously. Arteriolar vessels did not show such an increase in diameter, and furthermore their spontaneous contractile activity increased. These observations led to the idea that regulation of blood flow and blood pressure might be continued to some degree in the absence of central nervous control through enhanced activity of arteriolar vessels which just precede the capillary nets. Therefore a thorough study by direct microscopic observation of the behavior of arterial vessels in the following surgical and pharmacological denervation was made. The data support the hypothesis that loss of tone and loss of contractile activity in the large arterial vessels following denervation produce an increase of tone and activity in the smaller, more distally located vessels, thereby causing a redistribution of the site of regulation of flow through capillary nets. The largest arterial vessels showed and increase in average diameter of 38% after surgical denervation, while the terminal arterioles showed a decrease in average diameter of 24%. Neither phenoxybenzamine (Dibenzyline) norpentolinium (Ansolysen) were as effective as surgical denervation in producing relaxation of the large arterial vessels. Neither drug inhibited spontaneous contractile activity of the terminal vessels.