Increased expression of Gαq protein in the heart of streptozotocin-induced diabetic rats

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Abstract
Heart disease is one of the major cause of death in diabetic patients, but the thogenesis of diabetic cardio-myopathy remains unclear. In this experiment, to sess the significance of G protein signaling pathways in the pathogenesis of abetic cardiomyopathy, we analyzed the expression of G proteins and the tivities of second messenger dependent protein kinases: cAMP-dependent protein nase (PKA), DAG-mediated protein kinase C (PKC), and calmodulin dependent otein kinase II (CaM kinase II) in the streptozotocin induced diabetic rat art. The expression of Gαq was increased by slightly over 10% (P<0.05) in abetic rat heart, while Gαs, Gαi, and Gβ remained unchanged. The A activity in the heart did not change significantly but increased by 27%<0.01) in the liver. Insulin treatment did not restore the increased activity the liver. Total PKC activity in the heart was increased by 56% (P<0.01), and sulin treatment did not restore such increase. The CaM kinase II activity in e heart remained at the same level but was slightly increased in the liver 4% increase, P<0.05). These findings of increased expression of Gαq in the reptozotocin-diabetic rat heart that are reflected by the increased level of C activity and insensitivity to insulin demonstrate that alteration of Gαq y underlie, at least partly, the cardiac dysfunction that is associated with abetes.