RESUMO
This study evaluated the effect of chronic hyperglycemia on erythrocyte membrane Ca and Na/K-ATPase activities in streptozotocin-induced diabetic rats. The activity of Ca-ATPase was significantly lower in diabetic than in normal rats. Good glycemic control by insulin restored the Ca-ATPase activity to normal. By contrast, diltiazem, a calcium entry blocker, had no effect on the enzyme activity. Calmodulin stimulated Ca-ATPase activity in all groups of rats. Na/K-ATPase activity was not altered in diabetic rats, and no effects of either insulin or diltiazem treatments were observed. The results suggest that erythrocyte Ca-ATPase activity is decreased in diabetic rats and is normalized by good glycemic control.
Assuntos
Glicemia/análise , ATPases Transportadoras de Cálcio/sangue , Cálcio/antagonistas & inibidores , Diabetes Mellitus Experimental/sangue , Diabetes Mellitus Experimental/tratamento farmacológico , Diltiazem/uso terapêutico , Eritrócitos/enzimologia , ATPase Trocadora de Sódio-Potássio/sangue , Animais , Glicemia/efeitos dos fármacos , Glicemia/fisiologia , Calmodulina/farmacologia , Diabetes Mellitus Experimental/enzimologia , Diltiazem/farmacologia , Hemoglobinas Glicadas/análise , Masculino , Ratos , Ratos Wistar , Estreptozocina , Fatores de TempoRESUMO
The incorporation of [14C] U-glucose into glycogen by liver, kidney and skeletal muscle and that into total lipid by adipose tissue was studied in noninsulin-dependent genetically diabetic KK mice treated either with metformin (50 mg/kg) or water for 10 weeks. Results show that glycogen synthesis was increased in the skeletal muscle from metformin-treated mice. Liver and kidney glycogen synthesis was not affected by metformin. Glucose incorporation was significantly increased into lipid in metformin-treated mice. Insulin administration stimulated lipid synthesis in adipose tissue, but had no effect on muscle glycogen synthesis in metformin-treated mice. These data suggest that chronic metformin treatment potentiates the endogenous insulin action on glucose in skeletal muscle and adipose tissue, and thus confirm our previous results of increased glycogen synthesis by skeletal muscle in metformin-treated KK mice.
Assuntos
Diabetes Mellitus Experimental/metabolismo , Glicogênio/biossíntese , Lipídeos/biossíntese , Metformina/farmacologia , Animais , Glicemia , Glucose/metabolismo , Insulina/sangue , Insulina/farmacologia , Masculino , Camundongos , Camundongos MutantesRESUMO
Ornithine carbamoyltransferase (OCT) and arginase, but not arginine synthetase (AS), were detected in the body wall and gut tissues of the leech. The activities of these enzymes were not altered by starvation. The high activity of arginase in body wall is probably due to the association of the latter with botryoidal tissue. Hirudineans, which evolved from oligochaete ancestors, appear to have lost the citrulline-arginine segment of the urea cycle due to their ammonotelic mode of nitrogen excretion.
