High-salt diet impairs vascular relaxation mechanisms in rat middle cerebral arteries.
Male Sprague-Dawley rats were maintained on a low-salt (LS) diet (0.4% NaCl) or a high-salt (HS) diet (4% NaCl) for 3 days or 4 wk. PO(2) reduction to 40-45 mmHg, the stable prostacyclin analog iloprost (10 pg/ml), and stimulatory G protein activation with cholera toxin (1 ng/ml) caused vascular smooth muscle (VSM) hyperpolarization, increased cAMP production, and dilation in cerebral arteries from rats on a LS diet. Arteries from rats on a HS diet exhibited VSM depolarization and constriction in response to hypoxia and iloprost, failed to dilate or hyperpolarize in response to cholera toxin, and cAMP production did not increase in response to hypoxia, iloprost, or cholera toxin. Low-dose angiotensin II infusion (5 ng x kg(-1) x min(-1) i.v.) restored normal responses to reduced PO(2) and iloprost in arteries from animals on a HS diet. These observations suggest that angiotensin II suppression with a HS diet leads to impaired relaxation of cerebral arteries in response to vasodilator stimuli acting at the cell membrane.
Lombard
Julian H
JH
Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. jlombard@mcw.edu
Sylvester
Francis A
FA
Phillips
Shane A
SA
Frisbee
Jefferson C
JC
D000804:Angiotensin II / Q000008:administration & dosage; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002772:Cholera Toxin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000502:physiology; D016285:Iloprost / Q000494:pharmacology; D008297:Male; D020768:Middle Cerebral Artery / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D010100:Oxygen / Q000008:administration & dosage; D010847:Picolines / Q000494:pharmacology; D011460:Prostaglandins F / Q000378:metabolism; D011714:Pyrans / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage / Q000009:adverse effects*; D013929:Thromboxane B2 / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D010847:Picolines; D011460:Prostaglandins F; D011714:Pyrans; D017673:Sodium Chloride, Dietary; D014665:Vasodilator Agents; D000804:Angiotensin II; D005576:Colforsin; C061043:aprikalim; D013929:Thromboxane B2; D002772:Cholera Toxin; D000242:Cyclic AMP; D019205:GTP-Binding Protein alpha Subunits, Gs; D016285:Iloprost; D010100:Oxygen; C100006:prostaglandin F1