Increased sodium-calcium exchange in arterial smooth muscle of spontaneously hypertensive rats.
Hypertension
; 13(6 Pt 2): 890-5, 1989 Jun.
Article
em En
| MEDLINE
| ID: mdl-2737727
ABSTRACT
We compared sodium-calcium (Na-Ca) exchange in vascular smooth muscle between spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. Aortic rings of 11 SHR and 11 WKY rats aged 11-12 weeks were superfused with physiological saline, and isometric tension was measured. Systolic blood pressure was higher in SHR (174 +/- 12 mm Hg) than in WKY rats (132 +/- 4 mm Hg) 1) In the presence of 10 microM phentolamine, 10 microM verapamil, and 5 mM caffeine, reduction of ionized extracellular sodium concentration [( Na+]o) from normal (139.2 mM) to 1.2 mM (replaced by N-methyl-D-glucamine) caused an external Ca2+-dependent increase in tonic tension (calcium entry by Na-Ca exchange). The rate of increase was higher in SHR (35.4 +/- 3.9 mg/min) than in WKY rats (17.9 +/- 1.3 mg/min) (p less than 0.01). 2) In the presence of phentolamine, verapamil, and caffeine, relaxation from low-Na+ contraction was promoted by external calcium removal. The rate of relaxation was directly related to [Na+]o. The rates of relaxation at normal (139.2 mM) [Na+]o were higher in SHR than in WKY rats (p less than 0.05). The rates of relaxation at 1.2 mM [Na+]o (calcium extrusion by adenosine triphosphate-driven calcium pump) were not different between SHR (11.6 +/- 2.8 mg/min) and WKY rats (8.9 +/- 2.5 mg/min). The increase in the rates of relaxation from 1.2 mM to normal (139.2 mM) [Na+]o (calcium extrusion by Na-Ca exchange) was greater in SHR (34.9 +/- 6.6 mg/min) than in WKY rats (17.1 +/- 4.5 mg/min) (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ratos Endogâmicos SHR
/
Ratos Endogâmicos
/
Sódio
/
Cálcio
/
Hipertensão
/
Músculo Liso Vascular
Limite:
Animals
Idioma:
En
Revista:
Hypertension
Ano de publicação:
1989
Tipo de documento:
Article
País de afiliação:
Japão