title: Change in shear stress (Deltatau)/hydraulic conductivity (Lp) relationship after pronase treatment of individual capillaries in situ.
abstract: A complex glycoprotein meshwork covers the inner wall of blood vessels and is implicated in mechanotransduction of fluid shear stress (tau). A relationship between Deltatau and capillary Lp has been established. The purpose of this study was to evaluate Lp in response to Deltatau after exposing the capillary lumen to a mild, non-specific protease selected to disrupt its inner matrix. We hypothesized that Lp would not correlate with Deltatau after enzyme treatment. Frogs (Rana pipiens, n=69) were pithed and the mesentery was exteriorized. Lp was assessed at 30 cm H2O using the modified Landis technique after an abrupt, square wave Deltatau produced by a physiologically relevant increase in pressure. Perfusate solutions were 10 mg ml-1 BSA/frog Ringer's (Control) or 0.1 mg ml-1 pronase in BSA/Ringer's (1 min) then BSA/Ringer's alone (Test). Mean (+/-SE) control Lp following Deltatau was 2.2+/-0.2 x 10(-7) cm s-1 cm H2O-1 and individual values correlated positively with Deltatau (r=0.85, P<0.0001, n=41). After pronase, mean Test Lp (17.6+/-2.5 x 10(-7) cm s-1 cm H2O-1) was higher compared to control and Deltatau/Lp plots revealed two subsets of capillaries. Lp correlated strongly with Deltatau in capillaries with diameters<or=15 microm (r=0.91, P=0.0006, n=14) and also in a second subset of capillaries with diameters >15 microm (r=0.96, P=0.0001, n=8). Slopes were 3.9- and 8.7-fold higher, respectively, compared to control. These data suggest a protective role for luminal constituents of intact capillaries. Mechanisms involved in capillary responses to flow-induced, mechanical stimuli may be located in the cellular structures that form capillaries.
authors.affiliation: S314 Sinclair School of Nursing, University of Missouri-Columbia, Columbia, MO 65211, USA. DWilliams@health.missouri.edu
authors.forename: Donna A
authors.initials: DA
authors.lastname: Williams
mesh_terms: D000465:Algorithms; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D002196:Capillaries / Q000378:metabolism / Q000502:physiology*; D002199:Capillary Permeability / Q000502:physiology*; D018056:Hemorheology / Q000379:methods; D008297:Male; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D011402:Pronase / Q000378:metabolism; D011894:Rana pipiens; D013152:Splanchnic Circulation / Q000502:physiology*; D013314:Stress, Mechanical
chemical_list: D011402:Pronase