Role of transmural pressure in local regulation of blood flow through kidney

Abstract

In the kidney of the anesthetized dog, the pressure in an occluded hilar lymphatic vessel was used as an index of tissue pressure. While elevation of renal vein pressure produced a large rise in lymphatic pressure, reduction of renal artery pressure had little effect. Similarly, while elevation of vein pressure at constant flow produced an almost equal rise in lymphatic pressure, large changes in blood flow and hence artery pressure had little effect, despite evidence of local regulation of resistance. Intra-arterial injection of vasoactive agents at constant flow, which produced large changes in renal artery pressure, had little effect on lymphatic pressure. Sudden transient increase in renal blood flow sometimes produced changes in perfusion pressure which could have resulted from active constriction subsequent to rise in transmural pressure. These findings provide little support for the tissue pressure theory of autoregulation but suggest that tissue pressure does participate in the vascular response to elevated vein pressure. The study also provides some evidence for a vascular myogenic response to change in renal vascular transmural pressure.