A Biological Assay for Calcitonin

Abstract

SUMMARY (1) Calcitonin preparations from acetone-dried thyroid were administered to rats by various routes. (2) Intravenous administration, especially by infusion, produced a much greater fall in plasma calcium than s.c. or i.p. injection. (3) The log dose-effect curves after i.v. injection or infusion showed no evidence of non-linearity over a 100-fold dose range and had highly significant slopes. (4) The potency ratio of two preparations was estimated by means of a (2+2) assay design using both i.v. infusion and single i.v. injection. There was satisfactory agreement. (5) The i.v. injection method is recommended for the routine assay of calcitonin. A simple assay schedule is given in the Appendix. (6) A unit of calcitonin activity is defined in terms of a standard preparation.

Correlations between biological activities and conformational properties for human, salmon, eel, porcine calcitonins and Elcatonin elucidated by CD spectroscopy

“…Elcatonin, salmon (s), eel (e), human (h) and porcine (p) calcitonins are currently used for the treatment of Paget's disease, hypercalcemia of malignancy and osteoporosis. The biological potency of these hormones is determined by their serum calcium-lowering activity (Kumar et al, 1965). Ultimobranchial calcitonins (eCT, sCT and the synthetic eel analogue E,CT) are more potent than thyroidal calcitonins (hCT and pc'r).…”

Effect of Age and Thyrocalcitonin on Myocardial Changes Induced by Sodium Sulfaacetylthiazole

“…Some animals were parathyroidectomized by cautery 1 week prior to the injection and 10 to 50 mMRC units of thyrocalcitonin dissolved in physiological saline was injected in some others subcutaneously in 2 equally divided doses daily for 7 days before the injection of Na-sulfaacetylthiazole and 7 to 10 days after the injection. At the end of this period the animals were sacrificed and blood samples were obtained into heparinized test tubes for the determination of plasma calcium by the method of Copp et al (1963) Kumar et al(1965).…”

Calcitonin Activity of Particulate Fractions of the Ovine Thyroid Gland

“…Hence, it was essential that a reliable biological assay for CT be developed in order to assess extent of purification at each stage of the isolation procedure. The rat and the mouse proved to be ideal test animals for assaying the hypocalcemic activity of CT preparations (Hirsch et al, i964;Kumar et al, 1965). Most researchers today utilize the rat assay of Hirsch et al (1964), or a modification of this method.…”

“…Its action is to markedly retard bone resorption as evidenced by the rapid decrease in blood calcium levels. When calcitonin is administered to rats, it produces a hypocalcemia which is manifest~d shortly after hormone administration and reaches a peak approximately one hour after the hormone injection (Hirsch et al, 1964; Kumar et al, 1965) and it is effective even in parathyroidectomized rats (Gudmundsson e~ al., 1966). Considerable evidence has been presented which indicates that CT inhibits the PTH-induced resorptive process both in vivo and in vitro.…”

“…This is followed by the addition of 2 ml of 0.2 N NaOH to both the "Reagent Blank" and the "Test" tubes followed by mixing of the con- Protein was determined by utilizing the method of Lowry (1951) as modified by Oyama and Eagle (1956). There are two distinct steps which lead to the final color with proteins (1) a reaction with copper in alkali, and (2) Kumar et al (1965) noted that the maximal hypocalcemic response after intravenous injection of calcitonin preparations occurred JO to 60 minutes after injection. They therefore selected 50 minutes as the standard Collection time for the second blood sample.…”