The Department of Biomedicine

BBB Seminar: Roger H. Adamson

Regulation of microvascular permeability: an in vivo perspective

Roger H. Adamson
Department of Physiology and Membrane Biology, University of California at Davis, CA, USA

The luminal glycocalyx and the tight junction strand of the microvascular endothelium provide a regulated barrier to the flow of solutes and water between blood plasma and the interstitium. The endothelial cells are held together by the adherens junctions. Both the tight and adherens junctions are closely associated with the peripheral actin cytoskeleton. An emerging concept is that regulation of the adherens junction via small GTPases is central to both basal and acute inflammatory permeability of the endothelium. Using single perfused microvessels of the rat mesentery we have tested these concepts in vivo where we control the perfusion pressure and bathing solutions and make accurate measurements of exchange surface area and fluxes of both solute and water. We find that regulation via the well-described cAMP dependent pathways is in parallel with regulation via a pathway tonically stimulated by sphingosine-1-phosphate (S1P) that activates the small GTPase Rac, and that S1P in blood plasma is derived primarily from erythrocytes.

Host: Rolf K. Reed, Department of Biomedicine