David G. Butler

Hormonal control of gluconeogenesis in the North American eel (Anguilla rostrata)

Abstract Hypophysectomy of fresh water eels caused liver glycogen depletion. Hydrocortisone increased liver and muscle glycogen, and blood glucose in hypophysectomized and intact eels. Betamethasone is a strong glucocorticoid. Partial surgical adrenalectomy did not produce measureable changes in liver or muscle glycogen. However, liver glycogen decreased following injections of Amphenone. Plasma hydrocortisone concentrations, regulated through the pituitary interrenal axis, may be important for gluconeogenesis in North American eels.

(Na+K+)-ATPase activity in eel (Anguilla rostrata) gills in relation to changes in environmental salinity: Role of adrenocortical steroids

Abstract There was a positive linear correlation between gill (Na + K + )-ATPase activity and the difference between plasma and environmental sodium concentrations when eels were acclimated to a range of salinities. This suggested that enzyme activity is related to the energetics of the sodium pump. (Na + K + )-ATPase activity decreased after hypophysectomy (4 days) and increased when hypophysectomized eels were injected with cortisol or transferred to 50% sea water. Surgical adrenalectomy (4 days) failed to lower enzyme activity.

Dorsal aortic and organ blood flow decrease following Stanniectomy in freshwater North American eels (Anguilla rostrata LeSueur)

Dorsal aortic and regional blood flow rates were measured in freshwater North American eels using the radiolabeled microspheres method. Dorsal aortic blood flow was 28.6 ± 4.2 ml/min/kg (N = 6) in intact controls and 29.5 ± 3.3 ml/min/kg (N = 6) in sham-operated controls. The dorsal aortic blood flow decreased to 14.6 ± 1.5 ml/min/kg (N = 6), 12–16 days after the removal of the corpuscles of Stannius. Stanniectomy was followed by a lowered blood flow to most internal and peripheral (skin and fins) organs. Although dorsal aortic blood flow was reduced by 50%, there were few significant changes in the regional distribution of blood flow. The reduced gill and organ perfusion may, in part, lead to the electrolyte disturbances that are known to follow Stanniectomy.

Surgical adrenalectomy of a teleost fish (Anguilla rostrata LeSueur): Effect on plasma cortisol and tissue electrolyte and carbohydrate concentrations

Abstract Surgical adrenalectomy of starved freshwater North American eels was followed by changes in tissue carbohydrate and electrolyte concentrations, similar to those accompanying adrenal insufficiency in the Mammalia. Adrenalectomy was followed by a marked reduction in plasma cortisol concentrations thereby demonstrating an additional, direct effect of interrenal ablation. A meaningful evaluation of the results largely depends upon data for sham-operated controls.

Catecholamine-mediated pressor responses to angiotensin II in the Pekin duck, Anas platyrhynchos

Asp1,Val5-angiotensin II (AII) caused dose-dependent increases in aortic blood pressure (BP) when injected into anesthetized Pekin ducks. Norepinephrine (NE) and epinephrine (E) concentrations in arterial plasma were found to be elevated 1 min after injection of AII, when BP was peaking, while plasma levels of unconjugated dopamine (DA) did not undergo any consistent change. Pretreatment with 6-hydroxydopamine (6-OHDA) rendered ducks supersensitive to the pressor effect of injections of NE, but did not affect adrenal chromaffin cell granulation, plasma NE and E concentrations, or pressor responses to tyramine and AII. Depletion of endogenous NE and E stores, following treatment with reserpine, did not affect pressor responses to NE, but diminished pressor responses to tyramine and AII. The discrepancies in the responses of 6-OHDA-treated ducks and reserpinized ducks to exogenous NE and AII indicate different pressor mechanisms for the two hormones. It is suggested that mobilization of endogenous NE and E contributes to the rise in BP observed following AII injection.

Identification and distribution of the adrenocortical homolog, chromaffin tissue, and corpuscles of Stannius in Amia calva L

Abstract The identity and distribution of the corpuscles of Stannius (CS), the adrenocortical homolog (AH), and chromaffin tissue (CT) were examined in the holostean fish, Amia calva L. The CS were randomly scattered throughout the length of the kidneys as “white corpuscles” which were always associated with and often connected to the distal portion of the tubular nephrons. The AH was concentrated into smaller numbers of “yellow corpuscles” located near the posterior cardinal and renal veins in the anterior two-thirds of the kidneys. Each CS was encapsulated and divided into lobes and lobules of cells containing numerous granules which stained with periodic acid-Schiff (PAS). The yellow corpuscles were more richly vascularized and their loosely arranged cords of cells demonstrated Δ 5 -3 β -hydroxysteroid dehydrogenase activity, lacked PAS-positive granules, and possessed numerous lipid-filled vacuoles. The CT could be identified histochemically and was located beneath the endothelium of the posterior cardinal and renal veins. The phylogenetic significance of the distribution of CS and AH in A. calva was discussed, and it is suggested that because these tissues can be readily isolated from the kidneys, this organism is an ideal experimental animal for further studies on the function of these tissues in fishes.

Effects of temperature and feeding on intermediary metabolism in north american eels (Anguilla rostrata Lesueur)

Abstract 1. 1. When the temperature of acclimation for starved eels was raised from 5–15°C, blood glucose and muscle glycogen decreased whereas blood and muscle lactate and muscle pyruvate increased. 2. 2. At the higher temperature serum glutamic-oxaloacetic transaminase (SGOT) activity decreased and plasma protein increased. 3. 3. Lipolysis increased during starvation but plasma FFA and blood glycerol were the same at both 5 and 15°C. 4. 4. Feeding decreased tissue FFA and glycerol but had no measureable effect on SGOT or plasma protein concentrations. 5. 5. Glucose remained at the starvation level but liver and muscle glycogen increased, suggesting that at 15°C glucose was converted to glycogen and was also rapidly oxidized to meet the needs for increased metabolic activity.

Antidiuretic effect of arginine vasotocin in the Western painted turtle (Chrysemys picta belli)

Abstract A reduction in glomerular filtration rate (GFR), urine flow rate, and relative free water clearance occurred within 30 min of an intravenous injection of 10 ng/kg of arginine vasotocin. AVT increased the fraction of filtered sodium excreted ( C Na GFR ) but decreased the net rate of sodium exeretion.

Adrenalectomy of the painted turtle (Chrysemis picta belli): Effect on lonoregulation and tissue glycogen

Abstract Western painted turtles ( Chrysemis picta belli ) were adrenalectomized to show if adrenocortical steroids are necessary for electrolyte homeostasis. Two weeks after removal of the adrenal glands plasma Na had decreased by 13.7% whereas plasma K had increased by 22.1%. There were no significant changes in plasma Ca, Mg, or Cl. Plasma osmolarity increased by 4.4% while the blood hematocrit decreased by 31.9%. Muscle Na and Cl decreased by 27.1% and 26.7%, respectively, but there was no change in muscle K or in percentage of muscle water. Electrolyte changes observed 3 weeks after hypophysectomy were similar to those observed 2 weeks after adrenalectomy Treatment with Amphenone B or betamethasone was followed by some electrolyte changes, but injection of Metopirone failed to impair electrolyte balance. The only measurable response with aldactone was a significant increase in plasma calcium. Hepatic glycogen concentrations decreased after hypophysectomy and adrenalectomy and increased after treatment of intact turtles with betamethasone; Amphenone B had no effect.

Configuration of the medial and lateral segments of duck (Anas platyrhynchos) salt glands

Salt glands of the domestic duck Anas platyrhynchos differ from those of the herring gull Larus argentatus and other birds. In ducks, each salt gland consists of distinct medial and lateral segments. Centrally located drainage ducts that extend along the entire length of these medial and lateral segments collect hypertonic fluid secreted by an array of lobules. Each lobule is formed by a single mass of branched tubules in which the direction of capillary blood flow is opposite to that of the secreted fluid. This fluid drains from the medial segment through an external duct that opens into the nasal cavity at the base of the vestibular fold. A duct from the lateral segment loops and opens onto the surface of the nasal septum. The structure and function of the secretory cells is reviewed briefly within the context of our study of the configuration of duck nasal salt glands.