New Insight into Abnormal Muscle Vasodilatory Responses in Aged Hypertensive Rats by in vivo Nuclear Magnetic Resonance Imaging of Perfusion

Abstract

Objective: Increased peripheral arterial resistances and decreased maximum vasodilation are characteristic features of chronic hypertension. However, little data are available in the literature regarding the possible alterations in the temporal patterns of vasodilatory responses elicited by various stimuli. Design: This question was addressed by measuring skeletal muscle perfusion using nuclear magnetic resonance imaging combined with arterial spin labeling. Methods: Ninety-week-old male spontaneously hypertensive (SHR; n = 7) and normotensive Wistar Kyoto (WKY; n = 8) rats were studied, and calf muscle perfusion was measured at rest and during reactive hyperemia following total ischemia of 5 and 30 min duration. Results: Reactive hyperemia profiles differed according to duration of ischemia. In WKY rats, 5 min of ischemia induced a short peak of hyperemia lasting no more than 63 s, while 30 min of ischemia were followed by a prolonged hyperemic response of 261 s. In SHRs, after 5 min of ischemia, peak muscle arterial conductance was decreased to 0.5 ± 0.3 versus 0.9 ± 0.3 ml·min^–1·100 g^–1·mm Hg^–1 in the WKY rats (p < 0.05), as expected. After 30 min of ischemia, there was, in addition, a shortening of the hyperemic response duration. Time to post-ischemic half normalization of arterial conductance was 38 ± 24 s in the SHRs versus 149 ± 58 s in the WKY rats (p < 0.001). Conclusion: In vivo perfusion measurement not only confirmed the existence of a reduced maximum peripheral vasodilation in chronically hypertensive rats, it revealed a blunted hyperemic response after prolonged ischemia in the SHRs, which might be an important contributing factor to the increased sensitivity to ischemia in hypertension.

Journal

Journal ID (publisher-id): JVR

Journal ID (nlm-ta): J Vasc Res

Journal ID (doi): 10.1159/issn.1018-1172

Title: Journal of Vascular Research

Publisher: S. Karger AG

ISSN (Print): 1018-1172

ISSN (Electronic): 1423-0135

Publication date Subscription-year: 2006

Publication date (Print): February 2006

Publication date (Electronic): 16 February 2006

Volume: 43

Issue: 2

Pages: 149-156

Affiliations

^a NMR Laboratory, AFM-CEA, and ^bINSERM U582, Institute of Myology, IFR 14, Pitié-Salpêtrière University Hospital, Paris, France

Article

Publisher ID: 90944 Other ID: J Vasc Res 2006;43:149–156

DOI: 10.1159/000090944

PubMed ID: 16407660

Copyright statement: © 2006 S. Karger AG, Basel

License:

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Page count

Figures: 5, References: 35, Pages: 8

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Categories

Subject: Research Paper