An investigation was undertaken of the role of adrenergic influences on the transient change in colonic potential difference (p.d.) induced by handling in the rabbit. 2. P.d. was increased from 9-5 +/- 0-5 to 27-05 +/- 1-94 mV during a 2 hr period of handling and wrapping. Atropine and alpha-adrenergic block during this 2 hr period did not alter the magnitude of the response and the response in adrenalectomized animals was not significantly different from that of normal animals. 3. 'Total' adrenergic block and selective beta-adrenergic block abolished the change in p.d. with handling and infusion of an alpha-receptor agonist during the 2 hr period significantly reduced the response. 4. The changes in colonic p.d. with handling were greatly increased by the infusion of a beta-receptor agonist during the 2 hr test period. 5. The results indicate that the change in colonic p.d. with handling is a direct effect of the autonomic nervous system mediated via beta-receptors and that the changes were not related to the effects of circulating catecholamines or to changes in aldosterone production.
