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Summary
Glucagon inhibits the breakdown of bradykinin by enzymes called kininases in vitro. In dogs, glucagon increased urine flow and bradykinin excretion, suggesting kininase inhibition contributes to glucagon's effects.
Area of Science:
- Biochemistry
- Pharmacology
- Physiology
Background:
- Bradykinin is a peptide with important physiological roles.
- Kininases are enzymes that degrade bradykinin.
- Glucagon is a hormone with various metabolic functions.
Purpose of the Study:
- To investigate the effect of glucagon on bradykinin degradation by kininases.
- To explore the in vivo effects of glucagon on kinin excretion and related parameters.
Main Methods:
- In vitro experiments using kidney microsomes, erythrocytes, and plasma to assess glucagon's inhibition of bradykinin degradation.
- In vivo study involving intravenous infusion of glucagon in conscious dogs.
Main Results:
- Glucagon inhibited bradykinin degradation by kininases in kidney microsomes and erythrocytes in vitro.
- Glucagon showed less activity on plasma kininases and was inactive on purified pancreatic carboxypeptidase B.
- In conscious dogs, glucagon infusion increased urine flow and urine kinin excretion, while decreasing urine kallikrein excretion.
Conclusions:
- Glucagon inhibits kininase activity in vitro.
- In vivo, glucagon's effects on urine flow and kinin excretion suggest a role for kininase inhibition.
- Kininase inhibition by glucagon may contribute to its overall biological effects.