Peter K. T. Pang

The response of the hypophysectomized cyprinodont, Fundulus heteroclitus, to replacement therapy with cortisol: Effects on blood serum and sodium-potassium activated adenosine triphosphatase in the gills, kidney, and intestinal mucosa

Regulation of the inorganic constituents of the serum is nearly perfect in hypophysectomized Fundulus heteroclitus maintained in salt water, although serum Cl is lower. Chronic treatment with cortisol had no effect on serum Na or serum Ca; serum K and serum Cl decreased, serum inorganic PO4 and serum Mg increased. Na + K-ATPase activity increased in cortisol-treated fish in three organs that participate in osmoregulation: the gills, the kidneys (males only), and the intestinal mucosa. The increase in the gills can be correlated with a restoration of total Na exchange, previously reported by Mayer and Maetz (1967). The increased activity in the intestine, previously reported by Hirano et al. (1967) in Anguilla japonica, is presumably associated with the increased rate of Na turnover. Increased activity in the kidneys may reflect an increase in the glomerular filtration rate and (or) a restoration of renal Na retention. Other effects of cortisol are: a decrease in body weight, an increase in the abundance of circulating erythrocytes, leukocytosis after a single injection or short treatment that is regulated after longer treatment, and an increase in the relative weight of the liver that may be associated with gluconeogenesis. Cortisol had no effect on the relative size of the regressed gonads in either sex.

Pituitary regulation of serum calcium levels in the killifish, Fundulus heteroclitus L

Abstract Hypophysectomy produced hypocalcemia in male killifish, Fundulus heteroclitus , adapted to calcium-deficient sea water. Such changes in serum calcium levels were corrected by intraperitoneal injections of a homogenate of whole pituitary glands or by transplantation of the gland to the musculature of the caudal peduncle. Injections of homogenates of the anterior or posterior parts of the pituitary gland were also effective while the homogenate of the middle part of the gland produced a smaller change. Injections with prolactin at the doses of 5, 2.5, and 0.5 μg per gram body weight per injection significantly increased the serum calcium levels of the hypocalcemic hypophysectomized fish. Cortisol (2.5 μg per gram body weight per injection) and ACTH (0.05 IU per gram body weight) were also hypercalcemic, but lower doses of ACTH (0.02 and 0.005 IU per gram body weight) and two doses of MSH (2.5 and 5 μg per gram body weight) were without effect. It is suggested that either ACTH, prolactin or both may have hypercalcemic effects on fish in calcium-deficient environments.

Hypocalcemia and tetanic seizures in hypophysectomized killifish, Fundulus heteroclitus.

Summary Tetanic convulsions were observed in hypophysectomized Fundulus heteroclitus kept in calcium deficient but hyperosmotic conditions. Analysis of sera revealed a large decrease in total calcium and inorganic phosphate although sodium, potassium, and chloride were unaffected. These defects in calcium metabolism were corrected by returning the tetanic fish to a calcium-rich environment.

Failure of hog thyrocalcitonin to elicit hypocalcemia in the teleost fish, Fundulus heteroclitus

Abstract 1. 1. Hog thyrocalcitonin was administered to three physiologically different groups of male Fundulus heteroclitus at a dose of 0·2 mg (2–4 units) per g wt. of fish. Group 1 were intact fish maintained in salt water and fed; Group 2 were intact fish adapted to fresh water (low clacium) and starved for the final week; Group 3 were hypophysectomized fish maintained in salt water, and fed. 2. 2. Within each group there were no significant differences in serum-soluble calcium between controls and hormone-treated fish. 3. 3. Neither the time to autopsy (1–4 hr) nor the site of the injection (intraperitoneal or intravenous) had any effect. 4. 4. Differences between the three groups could be related to the state of maturation of the testes.

Calcium and fresh-water survival in the Euryhaline cyprinodonts, Fundulus kansae and Fundulud heteroclitus

Abstract 1. 1. The ability of calcuim ion to maintain the euryhaline cyprinodonts, Fundulus kansae and F. heteroclitus, in deionized water after hypophysectomy has been studied. 2. 2. Exposure of hypophysectomized F. kansae to deionized water caused a sharp drop in the osmotic pressure of the serum, dur in part to loss of serum sodium. The addition of calcium, with or without sodium, enabled the animals to maintain serum osmolarity at elvels significantly higher than the group held in deionized water. 3. 3. Exposure of hypophysectomized F. heteroclitus to deionized water solutions containing from 20 to 400 p.p.m. calcium, and in one case 200 p.p.m. sodium and 400 p.p.m. calcium, invariably led to fresh-water failure. F. heteroclitus is unable to maintain serum osmolarity in fresh water after hypophysectomy, and this loss of regulatory function is not affected by the addition of calcium.

The pituitary gland and calcium metabolism in Fundulus diaphanus (Teleosteii)

Tetanic seizures and hypocalcemia were observed in hypophysectomized Fundulus diaphanus maintained in fresh water. Serum sodium and chloride levels did not decrease in proportion to the decreases in serum calcium levels. It is suggested that the pituitary influence on serum calcium might be distinct from its effect on serum sodium or chloride.

Parathyroid glands and calcium and phosphate regulation in the lizard, Anolis carolinensis.

Abstract Serum calcium and phosphate values were measured in parathyroidectomized and sham-operated lizards, Anolis carolinensis . The parathyroidectomized animals showed significant hypocalcemia and hyperphosphatemia, which were accompanied by tetanic convulsions. Parathyroid extract reversed these symptoms in parathyroidectomized animals, eliminating tetanic seizures and returning the serum calcium and phosphate values to nearnormal. When similar doses of parathyroid extract were adminstered to sham-operated animals, there was no significant change in serum calcium or phosphate concentrations, although there was a trend toward hypercalcemia.

Lizard calcium metabolism: Lack of effect of mammalian calcitonin on serum calcium or phosphate levels in normal and parathyroidectomized lizards, Anolis carolinensis

Abstract Injection of porcine calcitonin (20 MRC mU/g body weight) had no effect on serum total calcium or inorganic phosphate levels in intact lizards, Anolis carolinensis. There was also no significant effect when parathyroidectomized animals were injected 3 or 48 hours after operation.

The twenty-four-hour seminal hydration response in goldfish (Carassius auratus)—I. sodium, potassium, calcium, magnesium, chloride and osmolality of serum and seminal fluid

Abstract 1. 1. Spermiation was induced in goldfish by an intraperitoneal injection of carp pituitary extract. The composition of the serum and seminal fluid was studied 24 hr after the injection. 2. 2. The semen volume was greater and the water percentage of the testes was 7·1±0·6(S.E.) higher in the extract-injected fish than in the controls. 3. 3. The osmolality and Na, K, Cl, Mg and Ca levels in the seminal fluid did not change in spermiation, and the seminal fluid was isosmotic to the serum. 4. 4. An increase in Na and K in the whole testes was greater than that accounted for by the addition to the seminal fluid. 5. 5. Serum Na increased 3·4±1·2 m-equiv./1; serum K decreased 0·48 ± 0·19 m-equiv./1; total serum protein decreased 0·56±0·12 g/100 ml. Theosmalality and Cl, Mg and Ca level in serum did not change.

Hypocalcemic activities in the ultimobranchial bodies of lungfishes, Neoceratodus forsteri and Lepidosiren paradoxa and teleosts, Fundulus heteroclitus and Gadus morhua

Abstract Acid extracts of homogenates of ultimobranchial bodies of Neoceratodus forsteri , Lepidosiren paradoxa, Fundulus heteroclitus , and Gadus morhua produced hypocalcemia in young rats. Tetany was observed in some rats 6 hr after injection with Fundulus ultimobranchial body extract.