Direct vascular actions of methyclothiazide and indapamide in aorta of spontaneously hypertensive rats.
In vitro experiments were designed to assess the inhibitory effect of the thiazide diuretics methyclothiazide (MCTZ), the hydrochlorothiazide (HCTZ), and the thiazide-related diuretic indapamide (IND) on contractile responses to norepinephrine (NE) and arginine vasopressin (AVP) of aortic rings from spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY). Changes in the tension of aortic ring preparations were measured isometrically. MCTZ (10(-4) M) induced endothelium-dependent inhibition of the vasoconstrictor responses to NE and AVP only in aortas from SHR, and the maximal vasoconstrictive effect of NE and AVP was decreased by 59 +/- 11% and 32.3 +/- 13%, respectively. Indapamide (10(-4) M) also induced endothelium-dependent inhibition of the contractile response to AVP in aortic rings from SHR, and the maximal vasoconstrictive effect of AVP was decreased by 33 +/- 5%. In contrast, HCTZ did not inhibit the contractile response to either NE or AVP, even at the highest concentration. This study provides evidence that methyclothiazide and indapamide inhibit the contractile response induced by norepinephrine and/or arginine vasopressin on SHR aortic preparations via an endothelium-dependent mechanism.
Colas
B
B
Laboratoire de pharmacologie et physiopathologie cardiovasculaire, faculté de médecine, Amiens, France.
Slama
M
M
Masson
H
H
Colas
J L
JL
Collin
T
T
Arnould
M L
ML
Hary
L
L
Safar
M
M
Andrejak
M
M
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D001127:Arginine Vasopressin / Q000008:administration & dosage / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology; D006852:Hydrochlorothiazide / Q000494:pharmacology; D066298:In Vitro Techniques; D007190:Indapamide / Q000494:pharmacology*; D008297:Male; D008736:Methyclothiazide / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000502:physiology; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D049993:Sodium Chloride Symporter Inhibitors / Q000494:pharmacology*; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000494:pharmacology
D000959:Antihypertensive Agents; D004232:Diuretics; D049993:Sodium Chloride Symporter Inhibitors; D014662:Vasoconstrictor Agents; D006852:Hydrochlorothiazide; D001127:Arginine Vasopressin; D007190:Indapamide; D008736:Methyclothiazide; D009638:Norepinephrine