α-Adrenoceptor-mediated pressor responses in pithed rats fed diets with different calcium contents

摘要: Results of many clinical and experimental studies indicate an inverse relationship between dietary calcium the prevalence hypertension. Our study was designed to evaluate alterations in arterial blood pressure changes alpha-adrenoceptor-mediated vascular reactivity normotensive Sprague-Dawley spontaneously hypertensive rats (SHR) fed from weaning (3 weeks life) three diets: normal (Ca 1%), low 0.1%), high 2.5%). The systolic diastolic pressures were measured weekly by tail cuff method. plasma levels animals also regularly colourimetric methods, evaluated measuring pressor responses alpha-adrenoceptor agonists pithed rats. These determinations carried out at end feeding periods (9 life 20 SHR) moments when maximal differences observed conscious diet those other two diets. Dietary deficiency increased both strains but supplements effective lower this only animals. altered administration not normal. low-calcium did modify either alpha(1)-adrenoceptor agonist, methoxamine, or alpha(2)-adrenoceptor B-HT 920 (5-allyl-2-amino-5,6,7, 8-tetrahydro-4H-thiazolo-(4,5-D)-acepin-dihydrochloride, talixepole), On contrary, high-calcium caused a definite decrease alpha(1)- alpha(2)-adrenoceptor-mediated strains. vasoconstrictor 9-week old 20-week SHR, none 15-week although age high- observed. results suggest that mechanisms implicated effects on are clearly different mechanisms, which bring about is deficient calcium. show causes variations reactivity, probably mechanism effect pressure.