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Heart dysfunction in chronic diabetes has been observed to be associated with depressed myofibrillar adenosine triphosphatase activities as well as abnormalities in the sarcoplasmic reticular and sarcolemmal calcium transport processes. The evidence has been presented to show that alterations in the expression of myosin isozymes and regulatory proteins as(More)
We have examined the direct effects of oxidant metabolites on cardiac sarcolemmal phosphoinositide phospholipase C which transduces signals from various receptors for the modulation of intracellular Ca2+ levels. The enzyme activity in rat cardiac sarcolemmal membranes that had been preincubated (10 min; 37 degrees C) with xanthine-xanthine oxidase, a(More)
Effects of adriamycin on rat heart sarcolemma were investigated by determining several membrane enzyme activities in the absence or presence of different concentrations of the drug. The adenylate cyclase activity was found to be stimulated by 0.001 and 0.01 microM of adriamycin whereas this enzyme activity was inhibited at 100 and 1000 microM concentrations(More)
Global ischemia in guinea-pig hearts for 60 to 90 min depressed microsomal and mitochondrial Ca2+ uptake activities. Reperfusion of the 60 min ischemic hearts resulted in incomplete recovery of contractile function and calcium uptake activities of both mitochondrial and microsomal fractions. On the other hand, reperfusion of the 90 min ischemic hearts(More)
Fibroblast growth factor-2 (FGF-2), administered to the isolated rat heart by perfusion and under constant pressure, is protective against ischemia-reperfusion (I-R). Here we have investigated whether FGF-2 cardioprotection: (a) is dependent on flow modulation; (b) is linked to effects on contractility; (c) is mediated by protein kinase C (PKC); and (d) is(More)
To understand cardiac dysfunction in diabetes, the activity of protein kinase C (PKC) and protein contents of its isozymes (PKC-alpha, -beta, -epsilon, and -zeta) were examined in diabetic rats upon injection of streptozotocin (65 mg/kg iv). The hearts were removed at 1, 2, 4, and 8 wk, and some of the 6-wk diabetic animals had been injected with insulin (3(More)
Earlier studies have demonstrated that palmitoyl carnitine (PC), a long chain acyl carnitine, accumulates in the ischemic myocardium. Although perfusion of hearts with PC is known to induce contractile dysfunction which resembles ischemic contracture, the mechanisms underlying this derangement are not clear. In this study, we examined the effect of(More)
BACKGROUND Large transmural myocardial infarction (MI) leads to maladaptive cardiac remodeling and places patients at increased risk of congestive heart failure. Angiotensin II, endothelin, and alpha1-adrenergic receptor agonists are implicated in the development of cardiac hypertrophy, interstitial fibrosis, and heart failure after MI. Because these(More)
The phospholipase D (PL D), which catalyzes the formation of phosphatidic acid (PA), was studied in rat myocardium using 14C-labelled phosphatidylcholine (PC) as an exogenous substrate. Subcellular distribution experiments indicated the presence of PL D in particulate fractions only. Different procedures for the isolation of purified cardiac subcellular(More)
Several studies have suggested that myocardial phospholipase D (PLD) and its hydrolytic product, phosphatidic acid (PtdOH), may regulate Ca2+ movements and contractile performance of the heart. Since abnormal intracellular Ca2+ handling is a major factor of myocardial dysfunction in chronic diabetes, we examined subcellular changes in PLD activity in(More)