Pancreatic glucagon secretion during a short period of hemorrhage in anesthetized dogs

Effect of [1-Sar,8-Thr]-angiotensin II on the hyperglycemic response to hemorrhage in adrenodemedullated and guanethidine-treated rats

The present experiments were designed to further investigate the action of an angiotensin II antagonist on the hyperglycemic response to hemorrhage (1.2 ml/100 g b.wt./2 min). The animals were divided into 3 experimental groups; (1) sham-operated animals submitted to intravenous administration of [1-Sar,8-Thr]-angiotensin II (sarthran), an antagonist of angiotensin II (750 ng/100 g b.wt. as a bolus plus an infusion of 25 ng/100 g b.wt./min over 30 min), which greatly attenuated (51.8% lower than controls; P < 0.01) the hyperglycemic response to hemorrhage; (2) animals submitted to adrenodemedullation which decreased the hyperglycemic response to hemorrhage by 64% (P < 0.01). However, sarthran infusion into adrenodemedullated rats caused a 38.5% further decrease in hyperglycemic response to hemorrhage (P < 0.01); and (3) intact animals submitted to blockade of sympathetic noradrenergic pathways by treatment with guanethidine (10 mg/100 g b.wt.), which greatly decreased the baseline value of plasma glucose (64.1 +/- 3.5 mg% vs. 125.3 +/- 4.5 mg%, P < 0.01), and reduced the hyperglycemic response to hemorrhage by 34% (P < 0.01). Sarthran infusion into guanethidine-treated rats caused a further 34% decrease in hyperglycemic response to hemorrhage (P < 0.01). These data indicate that angiotensin II has a direct hyperglycemic effect in addition to its action on sympathetic nervous system activation and adrenomedullary secretion.

Adrenocorticotrophic hormone, cortisol and catecholamine concentrations during insulin hypoglycaemia in dogs anaesthetized with thiopentone

Glucose homeostasis is maintained by complex neuroendocrine control mechanisms. Increases in plasma concentrations of various glucose-raising hormones such as glucagon, catecholamines, adrenocorticotrophic hormone (ACTH), and cortisol are observed under certain conditions associated with stress (haemorrhage and hypoglycaemia). The purpose of this study was to determine the effect of thiopentone anaesthesia on the catecholamine, ACTH and cortisol response to insulin hypoglycaemia in dogs. Blood sugar (BS), plasma catecholamine, and ACTH, and serum cortisol concentrations were measured during the course of (1) an intravenous insulin test (ITT) and (2) an ACTH test in conscious and in anaesthetized fasted dogs. During the ITT, the anaesthetized dogs showed a moderate resistance, compared with conscious dogs, to the hypoglycaemic action induced by insulin (blood sugar concentration 30 min after insulin injection: 2.91 +/- 0.25 vs 1.93 +/- 0.12 mM.L-1; P < 0.01). In addition, decreased epinephrine (220 +/- 27 vs 332 +/- 32 pg.ml-1), ACTH (65 +/- 6 vs 90 +/- 5 pg.ml-1) and cortisol (4.48 +/- 0.3 vs 6.25 +/- 0.5 micrograms.ml-1) concentrations were detected 60 min after insulin injection (P < 0.01). The norepinephrine response to hypoglycaemia was not altered by anaesthesia (273 +/- 33 vs 325 +/- 25 pg.ml-1). Anaesthetized dogs showed a decreased cortisol response to ACTH at 45 min (5.68 +/- 0.54 vs 8.87 +/- 0.47 micrograms.ml-1) when compared with control dogs (P < 0.001). Haemodynamic variables during anaesthesia showed little changes (P < NS); while respiratory rate was altered (P < 0.01 between 60 and 105 min).(ABSTRACT TRUNCATED AT 250 WORDS)