Chronic high‐salt diet reduces very low frequency blood pressure variability in stroke‐prone but not in stroke‐resistant rats

Abstract

In previous studies we demonstrated that myogenic vascular function specifically affects very low frequency (VLF, 0.02–0.2 Hz) blood pressure variability (BPV) in rats. In addition, impaired cerebrovascular myogenic function has been associated with hemorrhagic stroke in stroke-prone spontaneously hypertensive rats (SHR-SP) on high-salt diet. Therefore, we hypothesized that VLF BPV is reduced in SHR-SP on high-salt diet but not in stroke-resistant spontaneously hypertensive rats (SHR-SR) or normotensive Wistar Kyoto rats (NT-WKY). NT-WKY (n=9), SHR-SR (n=14), and SHR-SP (n=13) received a high-salt diet (1% NaCl in drinking water) for 4 or 6 weeks before arterial blood pressure was recorded in conscious animals. Blood pressure values at the 4th and 6th week of high-salt diet were greater in SHR-SP than in SHR-SR and greater in SHR-SR than in NT-WKY. From the 4th to the 6th week of high-salt diet, VLF BPV tended to increase in NT-WKY (from 9.1±2.2 mmHg2 to 13.5±6.4 mmHg2, not sig.) and SHR-SR (from 14.6±1.4 mmHg2 to 21.6±2.0 mmHg2, not sig.). In contrast, VLF BPV significantly decreased during this time period in SHR-SP (from 20.2±2.8 mmHg2 to 11.8±3.8 mmHg2, p<0.05). These data suggest that reduced VLF BPV indicates impaired myogenic vascular function in SHR-SP on high-salt diet prior to hemorrhagic stroke. Supported by: AHA #0630329N