Autoregulatory patterns in the arteriolar network of cat mesentery.

The purpose of this study was to examine the distribution and extent of autoregulatory behavior among arterioles in the arcade network of the cat mesentery. We found that 71% of 169 arterioles studied dilated and 63% showed blood flow autoregulation with arterial pressure reduction to 55-60 mm Hg. There appeared to be a direct relation between the degree of dilation and the degree of autoregulation when individual vessels were compared (r = 0.71). The dilation of individual arterioles was also correlated with the degree of autoregulation of other vessels in the same field (r = 0.51). To a lesser extent, the degree of dilation of individual arterioles was correlated with the degree of dilation of other vessels in the same field (r = 0.30). In comparing vessels which dilated, the largest average response was found in preparations where all vessels dilated. On a percentage basis the small arterioles located distally in the network dilated more than the large arterioles located proximally. In preparations having both reactive and nonreactive arterioles to pressure reduction, the nonreactive vessels were usually located geographically in proximity to each other. The flow distribution in the arteriolar network remained relatively stable on pressure reduction; the total tissue area perfused by a first-order arteriole shifting by 3% on the average.