TY - JOUR
T1 - High calcium diet reduces blood pressure in exercised and nonexercised hypertensive rats
AU - Sallinen, Kirsimarja
AU - Arvola, Pertti
AU - Wuorela, Heikki
AU - Ruskoaho, Heikki
AU - Vapaatalo, Heikki
AU - Pörsti, Ilkka
PY - 1996/2
Y1 - 1996/2
N2 - The effects of long-term high calcium diet and physical exercise and their combined effects on the development of hypertension, plasma and tissue atrial natriuretic peptide, and arterial function were studied in spontaneously hypertensive rats with Wistar-Kyoto rats serving as normotensive controls. Hypertensive rats were made to exercise by running on a treadmill up to 900 m/day. Calcium supplementation was instituted by increasing the calcium content of the chow from 1.1% to 2.5%. During the 23-week study, calcium supplementation attenuated the rise in blood pressure in both trained and nontrained hypertensive animals, whereas exercise training had no significant effect on blood pressure. The high calcium diet alone was associated with reduced plasma and ventricular tissue contents of atrial natriuretic peptide, both of which were increased by exercise. Responses of mesenteric arterial rings in vitro were examined at the end of the study. Neither increased dietary calcium nor endurance training affected the contractile sensitivity of endothelium-intact preparations to potassium chloride or norepinephrine. However, a high calcium diet enhanced the arterial relaxation induced by the return of potassium to the organ bath upon precontraction with potassium-free solution, and also moderately augmented relaxations to acetylcholine, sodium nitrite, and isoproterenol. Exercise training did not affect the potassium relaxation rate, but enhanced responses to acetylcholine, isoproterenol, and sodium nitrite. In conclusion, enhanced arterial potassium relaxation, a response reflecting the function of the vascular sodium pump, paralleled well the long-term blood pressure lowering action of increased dietary calcium intake in exercised and nonexercised hypertensive rats. However, augmented arterial relaxation to agonists could also be observed in the absence of reduced blood pressure following regular physical exercise.
AB - The effects of long-term high calcium diet and physical exercise and their combined effects on the development of hypertension, plasma and tissue atrial natriuretic peptide, and arterial function were studied in spontaneously hypertensive rats with Wistar-Kyoto rats serving as normotensive controls. Hypertensive rats were made to exercise by running on a treadmill up to 900 m/day. Calcium supplementation was instituted by increasing the calcium content of the chow from 1.1% to 2.5%. During the 23-week study, calcium supplementation attenuated the rise in blood pressure in both trained and nontrained hypertensive animals, whereas exercise training had no significant effect on blood pressure. The high calcium diet alone was associated with reduced plasma and ventricular tissue contents of atrial natriuretic peptide, both of which were increased by exercise. Responses of mesenteric arterial rings in vitro were examined at the end of the study. Neither increased dietary calcium nor endurance training affected the contractile sensitivity of endothelium-intact preparations to potassium chloride or norepinephrine. However, a high calcium diet enhanced the arterial relaxation induced by the return of potassium to the organ bath upon precontraction with potassium-free solution, and also moderately augmented relaxations to acetylcholine, sodium nitrite, and isoproterenol. Exercise training did not affect the potassium relaxation rate, but enhanced responses to acetylcholine, isoproterenol, and sodium nitrite. In conclusion, enhanced arterial potassium relaxation, a response reflecting the function of the vascular sodium pump, paralleled well the long-term blood pressure lowering action of increased dietary calcium intake in exercised and nonexercised hypertensive rats. However, augmented arterial relaxation to agonists could also be observed in the absence of reduced blood pressure following regular physical exercise.
KW - Animals
KW - Arteries/drug effects
KW - Atrial Natriuretic Factor/blood
KW - Blood Pressure/drug effects
KW - Body Weight
KW - Calcium/metabolism
KW - Calcium, Dietary/pharmacology
KW - Electrolytes/metabolism
KW - Heart Rate
KW - Hypertension/pathology
KW - Intracellular Membranes/metabolism
KW - Male
KW - Physical Conditioning, Animal
KW - Rats
KW - Rats, Inbred SHR
KW - Rats, Inbred WKY
KW - Vasoconstrictor Agents/pharmacology
KW - Vasodilator Agents/pharmacology
U2 - 10.1016/0895-7061(95)00333-9
DO - 10.1016/0895-7061(95)00333-9
M3 - Review Article
C2 - 8924264
VL - 9
SP - 144
EP - 156
JO - American Journal of Hypertension
JF - American Journal of Hypertension
SN - 0895-7061
IS - 2
ER -