The release of 5‐hydroxytryptamine from rabbit small intestine in vitro

Abstract

SUMMARY1. A method is described by which the lumen of intestinal segments may be perfused separately and simultaneously under identical conditions of perfusion pressure and temperature, and the rate of appearance of 5-hydroxytryptamine (5-HT) into the serosal fluid measured.2. 5-HT appeared in the serosal fluid from quiescent segments of rabbit intestine at a rate of about 4 0 ng/cm intestine/hr and about 14-0 ng/cm intestine/hr from segments performing active peristaltic movements.3. For both quiescent and active segments, when the perfusion fluid contained a monoamine oxidase inhibitor, nialamide (Niamid), the rate of appearance of 5-HT was increased and if, in addition, 5-HT was present in the perfusion fluid the rate of appearance of 5-HT in the serosal fluid was even greater.4. The rate of appearance of 5-HT from the intestine of rabbits pretreated with reserpine was about 08 ng/cm intestine/hr and Niamid only slightly increased this rate. However, if 5-HT as well as Niamid were present the rate of appearance of 5-HT was about 6-0 ng/cm intestine/hr. 5. Possible explanations for these findings are discussed.

Effect of Propranolol on the Release of Choline From Guinea-Pig Small Intestine in Vitro

“…They were stunned by a blow on the head and decapitated. The small intestine was removed and four adjacent segments, each about 9 cm in length, were taken as described by Gwee & Yeoh (1968). Each segment was mounted in an organ bath according to the procedure described by Yeoh & Lee (1968).…”

“…Both the mucosal and serosal surfaces of the intestinal segments were bathed in solutions of the same composition (Gwee & Yeoh, 1968). The solutions were aerated with 95% O2 and 5% C 0 2 and maintained at 38°C.…”