| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1989: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1988: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Hypertension and congestive heart-failure are often observed in patients with diabetes, and these complications are thought to be closely related to an alteration in the functions of sympathoadrenergic systems, which may be attributed to the long-lasting exposure to the high concentration of blood sugar. However, there has been no conclusive evidence supporting this possibility. Then, to address the question of whether the sympathoadrenergic functions are influenced by the exposure to high concentration of glucose, chromaffin cells isolated from bovine adrenal medulla were cultured in the medium containing high concentration of glucose (7-21 days), and the amount of catecholamines within these cells was then determined. In consequence, catecholamine content in the cells maintained in the normal culture medium was markedly decreasing as a function of the culture days. In contrast, the decrease in catecholamine content was no more observed when the cells were maintained in the high-gluco
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se medium. However, the same concentrations of other sugars, such as sucrose and raffinose, failed to prevent a decline in the cellular content of catecholamines under the same culture conditions.
It therefore seems conceivable that the turnover of catecholamines in the adrenal chromaffin cell is thought to be directly affected by the exposure to high concentration of glucose. On the other hand, we have examined the effects of hypoglycemic sulfonylureas on the secretion and the biosynthesis of catecholamines in cultured chromaffin cells, and found that these drugs inhibited both the secretion and the biosynthesis. Furthermore, sulfonylureas were also shown to inhibit the calcium uptake into the cells. Since the biosynthesis as well as the secretion of catecholamines is well known to require the influx of calcium ions into the cells, it therefore seems likely that sulfonylureas inhibits both catecholamine secretion and biosynthesis in adrenal chromaffin cells, probably through their inhibitory actions on the calcium influx into the cells. Less
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