Differential Central Modulation of the Baroreflex by Salt Loading in Normotensive and Spontaneously Hypertensive Rats
作者:
Ayumu Ono,
Tomoyuki Kuwaki,
Mamoru Kumada,
Toshiro Fujita,
期刊:
Hypertension
(OVID Available online 1997)
卷期:
Volume 29,
issue 3
页码: 808-814
ISSN:0194-911X
年代: 1997
出版商: OVID
数据来源: OVID
摘要:
In salt-sensitive hypertensive animal models and human subjects compared with their salt-resistant counterparts, sympathetic activity is abnormally enhanced during a high salt diet. We examined whether salt loading differentially modulates the arterial baroreceptor reflex (ABR), a major control mechanism of arterial pressure and sympathetic vasomotor activity, in young normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR). Six-week-old WKY and SHR were fed a normal (0.66%) or high (8.00%) salt diet for 4 weeks. After the diet regimen, baseline levels of mean arterial pressure (MAP), renal sympathetic nerve activity (RSNA), and the overall and central properties of the ABR were compared among the four groups of rats under halothane anesthesia. In WKY, a high salt diet did not affect baseline arterial pressure and RSNA but potentiated the ABR, as evidenced by an increase in the maximal slope of MAP-RSNA and MAP-heart rate relationships. In SHR, by contrast, salt loading accelerated hypertension and sympathetic overactivity and impaired the ABR. Salt-induced modulation of the ABR was associated with that of the central property, since reflex inhibition of RSNA by stimulation of the aortic depressor nerve was augmented in WKY and attenuated in SHR. These results suggest that differential modulation of the central mechanism subserving the baroreflex control of sympathetic activity at least partly accounts for the difference in salt sensitivity between WKY and SHR. (Hypertension. 1997;29:808-814.)
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