Primary culture of teleocalcin cells from rainbow trout corpuscles of Stannius: regulation of teleocalcin secretion by calcium.

This report describes a series of studies on the regulation of teleocalcin secretion by primary cultures of rainbow trout corpuscles of Stannius, endocrine glands believed to be unique to bony fishes. Teleocalcin release by these cultured cells was stimulated specifically by calcium in a dose-related fashion. Magnesium did not mimic the effects of added calcium and varying the osmotic pressure had no effect on hormone release. The addition of either ethyleneglycol-bis-(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) or cobalt chloride blocked the stimulatory effects of added calcium, whereas the calcium ionophore A23187 mimicked the effects of calcium on hormone release. Mammalian and piscine pituitary hormones (prolactin, growth hormone and gonadotrophic hormone) had no effect on teleocalcin secretion. Inconclusive results were obtained with the calcium channel blockers, verapamil and nifedipine. The results are discussed in relation to calcium-regulated secretion of calcitonin and parathyroid hormone, as well as the known physiological effects of teleocalcin in fish.