Experimental hyperthyroidism in dogs. Evaluation and effects on blood sugar, serum insulin and free fatty acids during glibenclamide infusion test.

The effects of hyperthyroidism on the BS, serum IRI and FFA responses to HB 419 were studied. Hyperthyroidism, induced by l-thyroxine administration, caused an increase in body temperature, respiratory rate, BS, serum FFA and PBI basal levels. Fasting serum cholesterol was reduced, and body weight, basal metabolic and heart rates, as well as basal serum insulin level failed to be affected. The hypoglycaemic response to HB 419 was moderately facilitated by hyperthyroidism, despite of inducing an impairment in the insulin secretory response. Serum FFA profile, similarly shaped in hyperthyroid dogs and in euthyroid controls, was shifted upwards by hyperthyroid condition. Results are discussed.