Abstract
Serum immunoreactive insulin (IRI) concentrations were measured in hypophysectomized
and normal dogs, during an i.v. glucose tolerance test (GTT) (1 g glucose per kg body
weight). Animals were awaken and as quiet as possible, after 16-18 hour fast. Two
blood samples were withdrawn by venipuncture, in postabsorptive state, within 1 hr
before the glucose load. Six blood samples were taken after the glucose injection
(5, 15, 25, 45, 60 and 90 minutes after glucose load). Hypophysectomized dogs received
Cortisol therapy, subcutaneously (1 mg/kg body wt./day, for 14-16 days, in saline),
and the glucose tolerance tests with simultaneous measurement of IRI concentration
in serum were performed again. The last Cortisol injection was given 1 hour before
glucose load.
Blood glucose and serum IRI concentration were measured according to Somogyi and Nelson,
and Morgan and Lazarow technique, respectively.
Glucose tolerance test was normal in dogs after hypophysectomy, whether before or
after Cortisol treatment. Serum IRI concentration was not changed after hypophysectomy
and/or Cortisol treatment in dogs, in post-absorptive state. Serum IRI concentration
curve after glucose injection was lower than normal in uninjected hypophysectomized
dogs, cortisol therapy leading it into normality.
Key words
Hypophysectomized Dogs - Cortisol Therapy - Serum Immunoreactive Insulin - Insulin-Glucose
Ratio
1 This work was partially supported by research grant No. 2304-a from the "Consejo
Nacional de Investigaciones Científicas y Técnicas" (República Argentina) and by a
research contract from the "Comisión Nacional de Energía Atómica" (Argentina).
