Vollmer R R, Balcita J J, Sved A F, Edwards D J
Department of Pharmaceutical Sciences, School of Pharmacy, Pittsburgh, Pennsylvania 15261, USA.
Am J Physiol. 1997 Nov;273(5):R1758-63. doi: 10.1152/ajpregu.1997.273.5.R1758.
Experiments were conducted in conscious male rats to determine whether hypoglycemia induced by insulin administration preferentially stimulated epinephrine (Epi) or norepinephrine (NE) adrenal medullary chromaffin cells. The release of Epi and NE from the adrenal medulla was continuously monitored using a microdialysis probe of novel design that had been inserted in the adrenal medulla approximately 16 h before the administration of insulin. Following insulin, 3 U/kg i.v., blood glucose declined and dialysate Epi levels rose. No measurable increment in dialysate NE was obtained. Similarly, plasma Epi increased with no detectable change in NE. Patterns of dialysate and plasma catecholamine changes were similar in two groups of animals that had been fed or fasted overnight before insulin treatment. However, the magnitude of the Epi increase was greater in the fasted animals. After recovery of the blood glucose concentration to preinsulin levels, dialysate and plasma catecholamine concentrations returned to control values. These experiments clearly demonstrate that adrenal medullary chromaffin cells that produce Epi are preferentially stimulated in response to insulin-induced hypoglycemia.
在清醒雄性大鼠身上进行了实验，以确定胰岛素给药诱导的低血糖是否优先刺激肾上腺素（Epi）或去甲肾上腺素（NE）肾上腺髓质嗜铬细胞。使用一种新型设计的微透析探针连续监测肾上腺髓质中Epi和NE的释放，该探针在胰岛素给药前约16小时插入肾上腺髓质。静脉注射3 U/kg胰岛素后，血糖下降，透析液中Epi水平升高。透析液中NE没有可测量的增加。同样，血浆Epi增加，而NE没有可检测到的变化。在胰岛素治疗前禁食或过夜喂食的两组动物中，透析液和血浆儿茶酚胺变化模式相似。然而，禁食动物中Epi增加的幅度更大。血糖浓度恢复到胰岛素给药前水平后，透析液和血浆儿茶酚胺浓度恢复到对照值。这些实验清楚地表明，产生Epi的肾上腺髓质嗜铬细胞在胰岛素诱导的低血糖反应中受到优先刺激。
