EFFECTS OF OESTRADIOL AND THYROXINE UPON PLASMA CALCIUM CONTENT OF A SHARK, SCYLIORHINUS CANICULA

Female lesser spotted dogfish given four intramuscular injections of oestradiol-17β, 3-benzoate, each at a dosage of 1 mg/kg body weight, showed a hypercalcaemic response, plasma total calcium increasing significantly from a mean control value of 10.3 meq/liter to 11.4 meq/liter in the experimental fish. When a solution of 1-sodium thyroxine was injected into the female dogfish at the same time as oestradiol-17β, 3-benzoate, no significant change in the concentration of plasma total calcium was found. The results closely paralleled those obtained with cod kept under the same experimental conditions and treated in the same manner, suggesting that the same basic response to oestrogens may be present in elasmobranchs as in teleosts, and other lower vertebrates. © 1969.