In vivo and in vitro effects of cicletanine in spontaneously hypertensive rats.
Oral treatment for 2 weeks with cicletanine [1,3-dihydro-6-methyl-7-hydroxy-3-(4-chloro-phenyl)furo(3,4-c)pyridine] at 30 mg/kg/day delayed the onset of hypertension in spontaneously hypertensive rats (SHR) (15.7 mmHg, p less than 0.001). This antihypertensive effect was increased when the animals were maintained on a high-salt diet (40.8 mmHg, p less than 0.001). The ability of cicletanine to alter calcium movements in phenylephrine (PE)- and angiotensin II (ANGIO)-triggered contraction was tested on isolated SHR aorta. PE (1 microM) and ANGIO (0.1 microM) induced a phasic contraction in calcium-free medium due to intracellular calcium release. Upon addition of calcium (2.5 mM) a second sustained (PE) or biphasis (ANGIO) contraction was observed. This second contraction was dependent on extracellular calcium influx. Cicletanine (0.1-0.3 mM) both reduced the phasic (77%, p less than 0.001 for PE; 68%, p less than 0.05 for ANGIO with cicletanine 0.3 mM) and the second contraction elicited by the two agonists (27%, p less than 0.001 for PE; 84%, p less than 0.001 for ANGIO with cicletanine 0.3 mM). These results suggest that in addition to its stimulatory effect on prostaglandin, a direct vascular action of cicletanine could also be involved in the antihypertensive properties of the drug.
Henri Beaufour Institute, Le Plessis-Robinson, France.
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M
Auguet
J M
JM
Guillon
S
S
Delaflotte
M
M
Le Hegarat
E
E
Pirotzky
F
F
Clostre
P
P
Braquet
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D001013:Aorta, Thoracic / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D004232:Diuretics / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D006973:Hypertension / Q000188:drug therapy*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D010656:Phenylephrine / Q000494:pharmacology; D011725:Pyridines; D051381:Rats; D011918:Rats, Inbred SHR
D000959:Antihypertensive Agents; D004232:Diuretics; D011725:Pyridines; D000804:Angiotensin II; D010656:Phenylephrine; C038068:cicletanine; D002118:Calcium