Central regulation of intestinal basal and stimulated water and ion transport by endogenous opiates in dogs.
The influence of intracerebroventricular (ICV) vs intravenous (IV) administration of (D-Ala2, Met5) enkephalinamide (Dalamide) on normal and stimulated (cholera toxin) jejunal fluxes of water, Na+, and K+ were investigated in dogs prepared with a Thiry-Vella (TV) loop. Intestinal transport in the TV loop and concomitant transit time were measured during an infusion (2 ml/min) of an isotonic electrolyte solution alone, or containing 0.4 micrograms/ml of cholera toxin (CT). Basal net water absorption was slightly, but significantly (P less than 0.05), increased during an ICV infusion of Dalamide at 0.5 ng/kg/min, while the secretory effects of cholera toxin were markedly reduced by nearly 75%. Similar effects were observed for Na+ and K+ movement. In contrast, Dalamide infused intravenously at a five times higher dose, ie, 2.5 ng/kg/min did not affect the control and CT-stimulated water and electrolyte movements. The jejunal loop transit times were halved during CT infusion. Similar values were observed under Dalamide ICV administration as well as during a five times higher dose of Dalamide administered intravenously. It was concluded that (1) Dalamide administered into the CNS, but not peripherally, increased the absorption of water, Na+, and K+, causing a net reduction in their secretion induced by cholera toxin; and (2) these effects did not result from changes in transit time. These results also suggest that Met-enkephalin can act in the brain to affect the intestinal transport of water and electrolytes in dogs.
D000818:Animals; D001921:Brain / Q000502:physiology*; D002772:Cholera Toxin / Q000494:pharmacology; D004285:Dogs; D004723:Endorphins / Q000502:physiology*; D004744:Enkephalin, Methionine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D005769:Gastrointestinal Motility; D007408:Intestinal Absorption; D007583:Jejunum / Q000502:physiology; D011188:Potassium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D014882:Water-Electrolyte Balance
D004723:Endorphins; D004744:Enkephalin, Methionine; C022118:enkephalinamide-Met, Ala(2)-; D002772:Cholera Toxin; D012964:Sodium; D011188:Potassium