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Reinforcement of arteriolar myogenic activity by endogenous ANG II: susceptibility to dietary salt
- Source :
- American Journal of Physiology-Heart and Circulatory Physiology. 279:H269-H278
- Publication Year :
- 2000
- Publisher :
- American Physiological Society, 2000.
-
Abstract
- The purpose of this study was to determine whether endogenous ANG II augments arteriolar myogenic behavior in striated muscle. Because circulating ANG II is decreased during high salt intake, we also investigated whether dietary salt could alter any influence of ANG II on myogenic behavior. Normotensive rats fed low-salt (0.45%, LS) or high-salt (7%, HS) diets were enclosed in a ventilated box with the spinotrapezius muscle exteriorized for intravital microscopy. Dietary salt did not affect resting arteriolar diameters. Microvascular pressure elevation by box pressurization caused greater arteriolar constriction in LS rats (up to 12 μm) than in HS rats (up to 4 μm). The ANG II-receptor antagonists saralasin and losartan attenuated myogenic responsiveness in LS rats but not HS rats. The bradykinin-receptor antagonist HOE-140 had no effect on myogenic responsiveness in LS rats but augmented myogenic responsiveness in HS rats. HOE-140 with the angiotensin-converting enzyme inhibitor captopril attenuated myogenic responsiveness to a greater extent in LS rats than in HS rats. We conclude that endogenous ANG II normally reinforces arteriolar myogenic behavior in striated muscle and that attenuated myogenic behavior associated with high salt intake is due to decreased circulating ANG II and increased local kinin levels.
- Subjects :
- Male
medicine.medical_specialty
Physiology
Myogenic contraction
Bradykinin
Blood Pressure
Endogeny
Rats, Inbred WKY
Losartan
Muscle, Smooth, Vascular
Angiotensin Receptor Antagonists
chemistry.chemical_compound
Arteriole
Physiology (medical)
Internal medicine
medicine.artery
Renin–angiotensin system
medicine
Animals
Myocyte
Muscle, Skeletal
Angiotensin II
Microcirculation
Skeletal muscle
Sodium, Dietary
Diet, Sodium-Restricted
Rats
Arterioles
Endocrinology
medicine.anatomical_structure
chemistry
cardiovascular system
Saralasin
Cardiology and Cardiovascular Medicine
Subjects
Details
- ISSN :
- 15221539 and 03636135
- Volume :
- 279
- Database :
- OpenAIRE
- Journal :
- American Journal of Physiology-Heart and Circulatory Physiology
- Accession number :
- edsair.doi.dedup.....729764027db44a13f34481ba4feb6feb