Salt-Induced hypertension in rats alters the response of isolated aortic rings to cromakalim
West Indian med. j
; West Indian med. j;50(1): 17-21, Mar. 2001. tab, gra
Article
in En
| MedCarib
| ID: med-326
Responsible library:
JM3.1
Localization: JM3.1; R18.W4
ABSTRACT
The effect of cromakalim, an opener of ATP-sensitive potassium (K atp) channel, on precontracted aortic rings from control and salt-loaded rats was studied in spague-Dawley rats. Salt-loading experiments involved the induction of hypertension by 6-week feeding of 80 g sodium chloride(NaCl)per kilogram(kg) diet while the control diet had 3 g NaCl per kg diet. Blood pressure and heart rate were determined by cannulation of a femoral artery under urethane/a-chloralose anaesthesia. Isolated aortic rings were mounted in tissue baths for isometric tension measurement. The sodium-potassium adenosine triphosphstase (Na-KATPase) pump activity was measured by potassium(K)-induced relaxation (with or without ouabain) following precontraction with 10-7 M noradrenaline.The KATP channel was studied by measuring the relaxation response to cromakalim,precontracted with either 10-7M noradrenalineor 60mM potassiumchloride(KCl). The Na- k ATPase pump appeared to be inhibited during salt loading. ATPase inactivation was found to be ouabain sensitive but did not seem to affect subsequent K - induced contraction. Cromakalim produced relaxation of noradrenaline precontracted rings frem the control rats; rings from salt-loaded rats showed significantly less relaxtion than control(p<0.05) under similar conditions. During K-induced precontraction, cromakalim produced a weak biphasic response in the control rings-an initial relaxation and then a reversal. Cromakalim produced further contraction of K-induced precontraction in salt-loaded group. The results suggest that ATP-sensitive potassium channels and Na-K ATPase pumps on the vascular smooth muscle membrane may be deactivated in the development of hypertension during salt loading.(AU)
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Collection:
01-internacional
Database:
MedCarib
Main subject:
Vasodilator Agents
/
Sodium-Potassium-Exchanging ATPase
/
Cromakalim
/
Hypertension
/
Muscle, Smooth, Vascular
Type of study:
Clinical_trials
Limits:
Animals
Language:
En
Journal:
West Indian Med J
/
West Indian med. j
/
West Indian medical journal
Year:
2001
Document type:
Article