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Myogenic vascular function affects very low frequency blood pressure variability in conscious rats and dogs
Author(s) -
Stauss Harald M,
Wong Brett J.,
Sheriff Don D.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a877-b
Subject(s) - nifedipine , vasoconstriction , myogenic contraction , medicine , blood pressure , sodium nitroprusside , vascular resistance , vascular smooth muscle , endocrinology , vasodilation , chemistry , nitric oxide , calcium , smooth muscle
Since myogenic vasoconstriction in isolated arteries is slower than norepinephrine‐induced vasoconstriction, we hypothesized that myogenic vascular function affects lower frequency components of blood pressure variability (BPV) than sympathetic modulation of vascular tone in rats and dogs. In conscious normotensive Wistar Kyoto rats (NT‐WKY, n=8) and conscious dogs (n=6), BPV was studied during control conditions, inhibition of myogenic function (i.v. infusion of nifedipine), and hypotension induced by sodium nitroprusside (Na‐NP). In dogs, the gain of the transfer function between mean blood pressure and total peripheral resistance, a measure of how much vascular resistance changes for a given change in pressure, was determined as an index of myogenic vascular function. Inhibition of myogenic vascular function, but not Na‐NP‐induced hypotension, significantly reduced VLF BPV (rats: 0.02–0.2 Hz; dogs: 0.01–0.07 Hz) in conscious rats (control: 3.6±1.1 mmHg 2 ; Na‐NP: 5.3±1.0 mmHg 2 n.s. vs. control; nifedipine: 1.4±0.3 mmHg 2 p<0.05 vs. control) and dogs (control: 38.1±9.3 mmHg 2 ; Na‐NP: 24.1±5.4 mmHg 2 n.s. vs. control; nifedipine: 13.1±4.5 mmHg 2 p<0.05 vs. control). In dogs, the normalized gain of the transfer function was high (>1) during control conditions exclusively in the VLF band and decreased to values <1 by nifedipine, but not by Na‐NP. In conclusion, myogenic vascular function affects VLF BPV in conscious rats and dogs. Supported by: NIH HL46314 and AHA #0630329N