ABSTRACT
The influence of thyrocalcitonin (TCT) on the enzymes alkaline phosphatase and inorganic pyrophosphatase in rat bone, kidney and intestine was studied.
The rats were injected with TCT every hour for 4 hours. They were divided into groups and were sacrificed 1 h after the first, second, third and fourth injection respectively. The plasma calcium was found to be reduced. Enzyme studies showed that: a) in tibia metaphysis homogenates alkaline phosphatase increased in response to TCT, to 198, 175, 154 and 183 per cent of the non-injected rats after 1, 2, 3, and 4 injections, respectively; inorganic pyrophosphatase was elevated to 356, 209, 221, 425 per cent after the same TCT injections. b) In kidney homogenates alkaline phosphatase was reduced to 75, 53, 79, 68 per cent of the non-injected rats after 1, 2, 3 and four doses, respectively; inorganic pyrophosphatase was reduced to 78, 56, 77 and 71 per cent after the same injections of TCT. c) In the jejunum, alkaline phosphatase was found to be 88.5, 71, 91 and 115 per cent of the untreated rats after 1, 2, 3 and 4 injections, respectively; pyrophosphatase in this tissue was found to be 105, 102, 102 and 113 per cent of the normal under the above conditions.
The results indicate: 1. TCT causes increases in alkaline phosphatase and inorganic pyrophosphatase activities in bone. The increase of pyrophosphatase is significantly more marked than the increase of alkaline phosphatase; 2. in kidney tissue, the action of TCT on these two enzymes is slower and their activities are equally reduced; 3. in the jejunum no significant effect of TCT on the activity of these two enzymes was observed.
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