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Distribution of Calcitonin-Sensitive Adenylate Cyclase Activity along the Rabbit Kidney Tubule
Daniélle Chabardés, Martine Imbert-Teboul, Madeleine Montégut, André Clique and François Morel
Proceedings of the National Academy of Sciences of the United States of America
Vol. 73, No. 10 (Oct., 1976), pp. 3608-3612
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/66651
Page Count: 5
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The adenylate cyclase [ATP pyrophosphatelyase (cyclizing), EC 220.127.116.11] sensitivity to salmon calcitonin in 11 different segments of the rabbit nephron was investigated using a micromethod for enzyme activity measurements in samples, each containing a single piece of tubule. The required segments were isolated by microdissection from collagenase-treated rabbit kidneys. The results were expressed as femtomoles of adenosine 3′:5′-cyclic monophosphate formed per mm of tubular length per 30 min of incubation time. In the presence of 0.1 μ g/ml of synthetic salmon calcitonin, it was found that eight segments exhibited no hormonal sensitivity whereas maximal responses were induced in three segments, the ``bright'' portion of the distal convoluted tubule, the cortical and the medullary portions of the thick ascending limb of the loop of Henle (stimulated over control activity ratios were 32, 11, and 27). The very high sensitivity to calcitonin of the adenylate cyclase contained in these three segments (0.01 ng/ml of salmon calcitonin inducing a 2-fold stimulation; half-maximal stimulation corresponding to about 0.3 ng/ml of salmon calcitonin) suggests that the distal convoluted tubule, as well as the cortical and medullary portions of the thick ascending limb of the loop of Henle represent physiological target structures of calcitonin action within the kidney.
Proceedings of the National Academy of Sciences of the United States of America © 1976 National Academy of Sciences