Role of the hepatic NaCl sensitive mechanism in NaCl homeostasis
| Project/Area Number |
06670055
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General physiology
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| Research Institution | Kagawa Medical School |
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Principal Investigator |
HOSOMI Hiroshi Kagawa Medical School Department of Physiology Professor, 医学部, 教授 (70030864)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1995: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1994: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | jejuno-jejunal reflex / intraluminal pressure / jejunal absorption / jejunal denervation / kainic acid / nucleus tractus solitarius / mesenteric nerve activity |
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| Research Abstract |
To examine the role of intestine in controlling body fluid homeostasis, following two experiments were conducted.
1) The aim of the first study was to investigate the role of the estrinsic nervous system in jejunal absorption under elevated intraluminal pressure of the jejunum. Anesthetized dogs were used in this experiment. Increase in intraluminal pressure from 0 to 70-100 mmHg decreased net absorption of fluid and NaCl. To examine the role of extrinsic nervous system in the depressed net jejunal absorption, jejunal afferent and efferent nerve activities were measured in response to the increase in intraluminal pressure. Both afferent and efferent nerve activities increased in response to the increase in intraluminal pressure. In the extrinsic denervated jejunal loop, the responses of net absorption were quite different from those in innervated jejunum. That is, in the denervated jejunal loop the elevation of intraluminal pressure converted jejunal absorption to jejunal secretion. The
… More
se results indicate that elevation of intraluminal pressure elicits the jejuno-jejunal reflex, and this mechanism counteracts jejunal secretion.
2) Effects of bilateral chemical inactivation of the nucleus tractus solitarius (NTS) by microinjection of kainic acid on fluid and NaCl absorption across the jejunum were examined in anesthetized Sprague-Dawley rats. Net fluid and NaCl absorption was significantly increased by the chemical inactivation of the NTS.To examine the efferent mechanism of the increased net absorption, mesenteric nerve activity was measured before and after the inactivation of the NTS.Mesenteric nerve activity was significantly increased after the bilateral inactivation of the NTS.Furthermore, absorption experiments were conducted in rats with pretreatment of atropine or yohimbine. In atropine treated rats, net jejunal absorption wa significantly increased by the inactivation of the NTS.However, the increase in net absorption induced by the inactivation of the NTS was completely abolished by pretreatment with yohimbine. These results suggest that the NTS has a tonic suppression on jejunal absorption through alpha2-adrenergic mechanism. Less
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Report
(2 results)
Research Products
(10 results)
