Delayed vascular compliance and fluid exchange in the canine intestine

Publisher Website
Google Scholar
Abstract
The hypothesis that delayed compliance (time-dependent volume change) is a significant part of the total intestinal tissue volume response to venous pressure changes was examined. Vascular volume (ml/kg tissue) of canine jejunal segments, measured by the constant infusion indicator-dilution technique, changed in proportion to flow [volume (ml/kg tissue) = 44 + 0.131.cntdot.flow (ml/min.cntdot.kg tissue)] and venous pressure (compliance = 2.55 ml/kg.cntdot.mmHg). Delayed compliance comprised 15-20% of the volume change following a change in venous pressure. Norepinephrine infusions decreased unstressed volume by 13 ml/kg and decreased vascular compliance to 1.76 ml/kg.cntdot.mmHg, whereas papaverine infusions increased the unstressed volume by 38 ml/kg. The capillary filtration coefficient (CFC) was 0.34 ml/kg.cntdot.mmHg.cntdot.min at 2 min after a venous pressure change and decreased 35% by 12 min. The data suggest that delayed compliance, on a short-term basis, may play a minor role in the intestinal vascular response and is not as important a compensatory mechanism as: passive elastic recoil, following changes in organ blood flow or venous pressure; unstressed vascular volume, changed by vascular smooth muscle tone; or transcapillary fluid exchange, following changes in capillary pressure.