| Co-Investigator(Kenkyū-buntansha) |
TAKATA Yutaka Faculty of Medicine, Kyushu University, Assistant, 医学部, 助手 (40163208)
UENO Michio Faculty of Medicine, Kyushu University, Assistant, 医学部, 助手 (40151823)
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| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1987: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1986: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Research Abstract |
Hypertension, obesity and glucose intorelance are commonly associated, suggesting common pathogenetic mechanisms one of which may be hyperinsulinemia. We investigated possible interactions of insulin with the sympathetic nervous system in both experimental and clinical studies.
1. Animal studies
In rabbits anesthetized with <alpha>-chloralose and urethane, intravenous load of 25% glucose solution (0.5 g/kg) resulted in transient increase in blood pressure (BP) and decreases in plasma norepinephrine (NE) and renal sympathetic nerve activity (RSNA) at 3 to 10 minutes after injection. Thereafter, these parameters remained around preload levels while plasma insulin (IRI) values were increased. Equimolar mannitol produced similar changes in BP and RSNA without IRI elevation.
Intracerebroventricular injection of insulin could not affect either BP or RSNA in anesthetized rabbits. Similarly, microinjection of insulin into ventromedial nucleus of the hypothalamus in rats could not elicit significa
… More
nt changes in BP and RSNA.
Further studies are needed to draw conclusions as to interactions between insulin and central sympathetic rervous function in relation to cardiovascular regulations.
2. Clinical studies
In male normotensive subjects, oral glucose load incrased plasma NE concentrations and did not change BP levels. In hypertensive men, however, the glucose load did not alter NE levels, accompanied with a reduction in BP. Changes in BP and NE values induced by 60゜ーhead-up tilting were not different between the two groups.
In obese subjects (BMI<greater than or equal>25), plasma glucose and IRI responses to glucose ingestion were larger and plasma NE was higher at 2 hr after than in non-obese control (age, BP, fasting glucose level-matched). Likewise, handgrip test induced larger increases in BP and plasma NE in the obese group compared with those in the control, while head-up tilting resulted in comparable changes in BP and plasma NE between botsimilar c
Therefore, the link between glucose metabolism and sympathetic function tested by oral glucose load may be indicated in obese subjects, but not in established hypertensives. Less
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