[Myoplasmic calcium-vasoconstriction coupling in the perfused caudal artery of adult spontaneously hypertensive rats. Effect of antihypertensive treatment].
In order to investigate whether smooth muscle intracellular calcium levels ([Ca2+]i) are related to hypertension and drug-induced changes in blood pressure, we studied basal perfusion resistance and basal [Ca2+]i and increases in perfusion pressure and [Ca2+]i using the fluorescent dye, fura-2 (dual wavelength excitation) in perfused tail artery. These were removed from 6 month old SHR previously treated (CAP + HCZ) for 10 weeks with captopril plus hydrochlorothiazide (44 and 22 mg/kg/day po, respectively). Separate groups received captopril (CAP) or hydrochlorothiazie (HCZ) alone, at similar doses, or no treatment (SHR). A fifth group of WKY normotensive rats did not receive any drug. Following determination of systolic arterial pressure (SAP) in awake rats, tail artery segments were removed and perfused at a constant flow rate with physiological salt solution plus fura-2/AM. Basal resistance and [Ca2+]i were determined. Then a dose-response curve for calcium chloride in the presence of a depolarizing concentration of potassium chloride was constructed. SAP was lowered in groups CAP + HCZ or CAP, but not in the group HCZ. Basal [Ca2+]i were similar in treated and untreated SHR and in WKY. Basal resistance to flow was lower in groups CAP + HCZ or CAP, and in WKY, than in untreated SHR. In depolarized arterial segments, vasconstrictor responses to perfusion with calcium chloride were lower in groups CAP + HCZ or CAP, and in WKY. Increases in [Ca2+]i were diminished in WKY rats. SAP measured in awake SHR and WKY was significantly correlated to basal and stimulated intracellular calcium-vasoreactivity coupling measured in vitro.
Robert
A
A
Laboratoire de Pharmacologie Cardiovasculaire, Faculté de Pharmacie, Nancy.
Thorin-Trescases
N
N
Oster
L
L
Capdeville-Atkinson
C
C
Atkinson
J
J
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001158:Arteries / Q000503:physiopathology; D002118:Calcium / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D004195:Disease Models, Animal; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013623:Tail / Q000098:blood supply*; D014661:Vasoconstriction / Q000502:physiology*
D000959:Antihypertensive Agents; D002118:Calcium
Couplage calcium myoplasmique-vasconstriction de l'artère caudale perfusée du rat spontanément hypertendu adulte. Effet du traitement antihypertenseur.