Drug‐induced Changes in Capillary Filtration Coefficient and Blood Flow in the Innervated Small Intestine of the Anaesthetized Cat

Abstract

1 A modification of the Folkow Technique for simultaneous measurement of blood flow and capillary filtration coefficient (CFC) in the cat jejunum is described. The modification retained the sympathetic innervation of the preparation, and in the present experiments, drugs were administered intravenously. 2 There is evidence that CFC is a cardiovascular quantity independent of blood flow or regional vascular resistance in these preparations. Low doses of drugs may affect CFC without altering the blood pressure, blood flow, or heart rate. 3 Under control conditions the CFC, a measure of functional exchange vessel area, was lower than previously reported for similar, but denervated preparations.

A COMPARISON OF THE EFFECTS OF BRADYKININ, 5‐HYDROXYTRYPTAMINE AND HISTAMINE ON THE HEPATIC ARTERIAL AND PORTAL VENOUS VASCULAR BEDS OF THE DOG: HISTAMINE H1 AND H2‐RECEPTOR POPULATIONS

“…Confirming previous observations (Andrews & Butterworth, 1958), the responses to 5-HT of both the arterial and portal beds were more variable than those to any substance hitherto investigated. This variability in response to 5-HT may depend upon the prevailing sympathetic vasoconstrictor tone (Page, 1957;Haddy, Gordon & Emmanuel, 1959;McCubbin, Kaneko & Page, 1962;Davies & Withrington, 1973) and the route by which the amine is administered (Biber, Fara & Lundgren, 1973;Richardson, 1974).…”

The Actions of Natural Secretin on the Small Intestinal Vasculature of the Anaesthetized Cat

“…The preparations used were similar to those described previously for the measurement of blood flow, changes in tissue volume and capillary filtration coefficient (CFC) in the small intestine (Folkow et al, 1963;Richardson, 1974 (Richardson, 1974).…”

“…The prepared loop of small intestine was inserted into a rhomboid-shaped Perspex plethysmograph, which was then sealed and connected to a recorder to measure changes in the volume of the tissue (Richardson, 1974). In the 'isolated' preparations, mean arterial perfusion pressure was measured with the same system from a 'T'-piece in the cannula, close to the point of cannulation of the superior mesenteric artery.…”

“…Changes in jejunal volume were recorded as described previously (Richardson, 1974), by a displacement technique, measuring the upthrust of fluid in continuity with the plethysmograph contents upon the sensor of an isometric transducer, Devices (Model 4151).…”

“…It has previously been demonstrated that changes in CFC may be evoked by vasoactive substances 9 adminstered in doses inadequate to affect the recorded intravascular pressures or the total blood flow through a tissue (Folkow et al, 1963;Richardson, 1974Richardson, , 1975aRichardson, , 1975b.…”