Effect of salmon calcitonin on plasma calcium and phosphorus in pregnant and non-pregnant guinea pigs.

The effect of salmon calcitonin (SCT) on plasma calcium ion activity (ICa) and inorganic phosphorus (Pi) was investigated in pregnant and non-pregnant guinea pigs. Basal plasma ICa and Pi were lower in pregnant compared to non-pregnant animals. Intravenous administration of SCT in doses ranging from 120 to 520 MRC mU . kg-1 resulted in hypocalcemia in both groups. Pregnant guinea pigs responded with a more pronounced and sustained hypocalcemia compared to non-pregnant animals. The observed effects on plasma Pi were less consistent, with hypophosphatemia evident only in the non-pregnant guinea pigs. It is suggested that the sensitivity of pregnant guinea pigs to the hypocalcemic effect of SCT may be a result of a higher rate of bone turnover.