AJP - Gastrointestinal and Liver Physiology, Vol 250, Issue 2 172-G176, Copyright © 1986 by American Physiological Society
Centrally mediated stimulation of jejunal water and electrolyte secretion by calcitonin in dogs
M. P. Primi and L. Bueno
The effects of intracerebroventricular versus intravenous injection of
salmon calcitonin (sCT) at a dose of 0.2 IU X kg-1 on jejunal fluxes of
water, Na+, and K+ were investigated before and after vagotomy or an
intravenous treatment with indomethacin (1 mg X kg-1) in dogs prepared with
a jejunal Thiry-Vella loop. Intestinal transport in the Thiry-Vella loop
and concomitant mean transit time were measured during an infusion (2 ml X
min-1) of an isotonic electrolyte solution and phenol red bolus injections.
Basal net water absorption was significantly (P less than 0.01) reduced by
51.7% from 2 to 3 h after intracerebroventricular administration of sCT,
Na+ absorption was reduced by 62.6%, and net flux of K+ was reversed from
absorption to secretion. A similar intravenous dose had no effect. Previous
treatment with indomethacin or bilateral thoracic vagotomy did not reduce
the water, Na+, and K+ secretory effects of centrally administered sCT,
whereas indomethacin per se appeared to reduce water and electrolyte
absorption. A significant (P less than or equal to 0.05) increase in mean
transit time was observed after intracerebroventricular but not intravenous
calcitonin (0.2 IU X kg-1), and this effect was abolished after vagotomy.
These results suggest that calcitonin may be involved in the central
control of intestinal secretion in dog, inasmuch as these effects were
mediated by different structures from those affecting intestinal motility.
