Effect of diltiazem on skeletal muscle 3-O-methylglucose transport in bacteremic rats

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Abstract
This study examined whether alterations in cellular Ca2+ regulation contribute to previously observed changes in skeletal muscle sugar transport during bacteremia. Fasted male rats received saline (control) or bacteria (4 X 10(10) Escherichia coli/kg) intraperitoneally. Twelve hours later, basal and insulin-mediated 3-O-methylglucose (3MG) transport was measured in isolated soleus muscles. Measurements of 3MG transport in the presence of cytochalasin b or at a low temperature (0.5 degree C) indicated that altered sugar transport in bacteremic rat muscles was not due to nonspecific membrane permeability changes. To determine the role of Ca2+ in the pathogenesis of altered sugar transport during bacteremia, rats were treated with the Ca2+ antagonist diltiazem (DZ, 0.6-2.4 mg/kg) at various times (0, 0 + 7.5, 10 h) after saline or bacterial injection. In bacteremic rats given 2.4 mg/kg DZ at 10 h, basal and insulin-mediated transport were similar to control values. This dose of DZ had little effect on control muscles. The addition of 20 microM DZ to the incubation media did not affect basal or insulin-mediated 3MG transport in bacteremic rat muscles. Addition of the Ca2+ agonist BAY K 8644 to the incubation media had no effect on sugar transport in bacteremic rat muscles but caused alterations in control rat muscles that were comparable to those observed in bacteremia. These results suggest that alterations in Ca2+ regulation could contribute to the previously observed changes in sugar transport in skeletal muscles from bacteremic rats.