Bank N, Lahorra M A, Aynedjian H S
Am J Physiol. 1987 Jan;252(1 Pt 1):E13-20. doi: 10.1152/ajpendo.1987.252.1.E13.
We examined the effect of calcium administration on renal hyperfiltration in streptozotocin-treated diabetic rats. Rats were studied 7-10 days after streptozotocin injection. Intrarenal infusion of CaSO4 in Ringer's solution had no effect on the hyperfiltration of the diabetic kidney. Infusion of insulin in a dose that did not effect hyperglycemia also had no effect on the hyperfiltration. However, when insulin and calcium were infused together, a rapid decrease in glomerular filtration rate, single-nephron filtration rate, glomerular hydraulic pressure, and renal plasma flow occurred. The contralateral control kidney was unaffected. Verapamil infusion had no significant effect in untreated diabetic rats, but immediately reversed the vasoconstriction induced by insulin plus calcium. Similar intrarenal insulin and calcium infusions had no effect in euvolemic or chronically salt-loaded nondiabetic rats. The observations indicate that renal vascular cells (probably preglomerular) are hyperresponsive to calcium in early insulin-dependent diabetes mellitus and that this response requires insulin. We suggest that decreased renal vascular tone in early insulin-dependent diabetes mellitus may be due in part to defective transmembrane calcium flux across vascular smooth muscle cells. Insulin appears to be required for calcium entry or mobilization, to initiate renal vascular smooth muscle contraction in diabetes.
我们研究了钙给药对链脲佐菌素诱导的糖尿病大鼠肾高滤过的影响。在注射链脲佐菌素7 - 10天后对大鼠进行研究。在林格氏液中肾内输注硫酸钙对糖尿病肾的高滤过无影响。输注不影响血糖水平的胰岛素剂量对高滤过也无影响。然而，当胰岛素和钙一起输注时，肾小球滤过率、单肾单位滤过率、肾小球液压和肾血浆流量迅速下降。对侧对照肾未受影响。维拉帕米输注对未治疗的糖尿病大鼠无显著影响，但能立即逆转胰岛素加钙诱导的血管收缩。类似的肾内胰岛素和钙输注对血容量正常或长期盐负荷的非糖尿病大鼠无影响。这些观察结果表明，在早期胰岛素依赖型糖尿病中，肾血管细胞（可能是肾小球前血管细胞）对钙反应过度，且这种反应需要胰岛素。我们认为，早期胰岛素依赖型糖尿病中肾血管张力降低可能部分归因于跨血管平滑肌细胞的跨膜钙通量缺陷。胰岛素似乎是钙进入或动员所必需的，以启动糖尿病状态下肾血管平滑肌的收缩。
