Effect of calcium concentration on collateral arteries from the hind limb of the dog.
Changes in extracellular calcium on collateral arteries were compared with noncollateral branch arteries from the normotensive extremity. Six weeks and 4 months after occlusion of the right superficial femoral artery, a collateral, a segment of branch artery from the opposite extremity and both anterior tibial arteries were removed. Exposure to calcium-free medium rapidly decreased the response of developing collaterals to l-epinephrine (10(-6) M) and initially increased the response by branch arteries. The fast response, dependent on intracellular calcium stores, decreased in collaterals but increased in branch arteries up to 40 min in calcium-free medium. The slow response, which is dependent on extracellular calcium, could not be sustained. Developing collateral and branch arteries responded similarly to [Ca++] 0.2 to 6.0 mM. Fast and slow components were unaffected in developing collaterals by calcium concentration. Fully developed collaterals were more sensitive to the effects of calcium depletion and to high and low calcium concentrations than developing collateral arteries. To evaluate the role of hypotension, anterior tibial arteries exposed to low blood pressure were compared with contralateral normal anterior tibial arteries. No differences were observed at 6 weeks or 4 months. The role of calcium in the response of developing collateral arteries differs from that in similarly sized branch arteries. These differences are not due to the pressure differential.
D000375:Aging; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology*; D004285:Dogs; D004837:Epinephrine / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects
D002118:Calcium; D004837:Epinephrine