Inhibition by amiloride of both adenylate cyclase activity and the Na+/H+ antiporter in fish erythrocytes

Mahé, Yann F.; Garcia-Romeu, F; Motais, R

doi:10.1016/0014-2999(85)90154-2

Cited by 96 publications

(49 citation statements)

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“…Several actions of the diuretic parent compound, amiloride have been demonstrated: an inhibition of Na+/H' and of Na+/Ca2+ exchange, an inhibition of adenylate cyclase activity (Mahe et al, 1985), a reduction ofthe affinity of ouabain for its binding sites and an inhibition of Na/K-ATPase activity (Kennedy et al, 1985). In rat and chick cultured cardiac cells, EIPA has been shown to be more specific than amiloride as an inhibitor of Na+/H+ exchange (Frelin et al, 1984).…”

Section: Resultsmentioning

confidence: 99%

Selective inhibition by ethylisopropylamiloride of the positive inotropic effect evoked by low concentrations of ouabain in rat isolated ventricles

Finet

Godfraind

1986

British J Pharmacology

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1 The biphasic positive inotropic effect of ouabain has been studied in rat ventricular strips in the presence of ethylisopropylamiloride (EIPA) an inhibitor of Na+/H+ exchange.2 EIPA (10-20IpM) depressed dose-dependently the high affinity component of the ouabain inotropic effect, whereas it did not significantly modify the low affinity inotropic effect related to high concentrations of ouabain. 3 At the EIPA concentrations studied, there was no observable modification of the inotropic effect of Bay K 8644 (IO nM, 0.3 pM) or of isoprenaline (10 nM, 1 pM). 4 These results indicate that the inotropic effect of ouabain resulting from its interaction with high affinity sites is selectively sensitive to EIPA.

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Section: Resultsmentioning

confidence: 99%

Selective inhibition by ethylisopropylamiloride of the positive inotropic effect evoked by low concentrations of ouabain in rat isolated ventricles

Finet

Godfraind

1986

British J Pharmacology

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“…Two hypotheses could be put forward to explain this result: (1) An increase in erythrocyte release due to spleen contraction stimulated by catecholamines as previously shown in the antarctic fish Pagothenia borchgrevinky (Wells et al 1989) and in rainbow trout (Wells & Weber 1990). (2) An increase in erythrocyte volume due to the adrenergic activation of Na + /H + exchange mechanism across the cell membrane; if this was the case, the subsequent increase in intracellular pH could enhance hemoglobin oxygen affinity (Mahé et al 1985, Borgese et al 1986). These 2 mechanisms could contribute to facilitate oxygen transport to tissues as a compensation of the decrease in oxygen availability.…”

Section: Discussionmentioning

confidence: 99%

Effects of hypoxia and subsequent recovery on turbot Scophthalmus maximus: hormonal changes and anaerobic metabolism

Pichavant

Maxime²,

Thébault³

et al. 2002

Mar. Ecol. Prog. Ser.

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Hormonal changes, substrate mobilization and energy metabolism were studied in turbot Scophthalmus maximus exposed to 3 hypoxic conditions (oxygen partial pressure in water, PwO 2 = 90, 60 and 30 mm Hg) followed by recovery under normoxia. Measurements of the blood pH, total CO 2 concentration, arterial oxygen partial pressure, hematocrit, glucose, lactate, and 'stress' hormones (cortisol, adrenaline and noradrenaline) plasmatic concentrations were performed. Highenergy phosphorylated compounds, glycogen, glucose and lactate concentrations were also determined in liver and white muscle tissues. Exposure to 90 or 60 mm Hg did not induce any major physiological change, as hyperventilation by itself could compensate for the decrease in water oxygen tension. At 30 mm Hg, marked increases in cortisol, adrenaline and noradrenaline concentrations, associated with a decrease in blood arterial oxygen partial pressure, were observed. During exposure to 30 mm Hg, turbot resorted to anaerobic metabolism, resulting in liver glycogen depletion and lactate production. This mechanism appeared to be efficient enough to produce energy, as no significant change in phosphorylated compounds and adenylate energy charges in muscle and liver could be observed. These results indicate an absence of metabolic depression in turbot down to 30 mm Hg and confirm the high capacity of this species to cope with low water oxygen tension.

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“…Binding of catecholamine to the membrane-bound β-AR triggers an adenylate cyclase-catalysed synthesis of cAMP (Mahe et al, 1985), which in turn stimulates protein kinase A to activate the βNHE (Guizouarn et al, 1993). Accordingly, we tested whether the cause of the seasonally reduced adrenergic responsiveness lay in the transduction pathway linking the receptor with the transporting effector using chemical compounds known to stimulate the βNHE by intervening at different points on a possibly long transduction pathway.…”

Section: Comparison Of the Effects Of Isoproterenol Forskolin Dibutmentioning

confidence: 99%

Seasonality of the red blood cell stress response in rainbow trout(Oncorhynchus mykiss)

Koldkjær

Pottinger

Perry

et al. 2004

Journal of Experimental Biology

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The β-adrenergic stress response in red blood cells (RBCs) of rainbow trout shows seasonal changes in expression. We have explored the mechanisms underpinning this response by following, over a period of 27·months, changes in β-adrenergic receptor (β-AR) binding characteristics, β-adrenergically stimulated RBC Na + /H + exchanger (βNHE) activity, together with β-AR and βNHE mRNA levels and plasma steroid hormone and lactate levels. These parameters were measured at approximately monthly intervals in a single population of fish held under semi-natural conditions. Membranebound, high-affinity β-ARs were present in RBCs at all sampling times, varying from 668±112·receptors·cell -1 to 2654±882·receptors·cell -1 (mean ± S.E.M.; N=8). βNHE activity, however, was reduced by 57% and 34% in December 1999 and February 2001, respectively, compared with an otherwise sustained influx that averaged 110.4±2.3·mmol·l -1 ·RBCs·h -1 (N=119). Only one reduction coincided with a spawning period but both were preceded by transient increases in circulating testosterone. βNHE activity measured under standard conditions was not correlated with the number or affinity of β-ARs nor with water temperature, but both β-AR numbers and βNHE activity were positively related to their respective mRNA levels (P=0.005 and 0.038, respectively). Pharmaceutical intervention in the transduction cascade linking the β-AR and βNHE failed to indicate any failure of the transduction elements in RBCs displaying low βNHE activity. Similarly, we failed to demonstrate any link between seasonal cortisol fluctuations and seasonally reduced βNHE activity. However, the βNHE activity of age-separated RBC fractions showed that younger RBCs had a significantly higher βNHE response than older RBCs, consistent with the seasonal reductions in βNHE being linked to turnover of RBCs and erythropoiesis. Testosterone is known to induce erythropoiesis and we conclude that seasonal reductions in βNHE are not caused by changes in β-AR numbers but may be linked to testosterone-induced erythropoiesis.

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Inhibition by amiloride of both adenylate cyclase activity and the Na+/H+ antiporter in fish erythrocytes

Cited by 96 publications

References 10 publications

Selective inhibition by ethylisopropylamiloride of the positive inotropic effect evoked by low concentrations of ouabain in rat isolated ventricles

Selective inhibition by ethylisopropylamiloride of the positive inotropic effect evoked by low concentrations of ouabain in rat isolated ventricles

Effects of hypoxia and subsequent recovery on turbot Scophthalmus maximus: hormonal changes and anaerobic metabolism

Seasonality of the red blood cell stress response in rainbow trout(Oncorhynchus mykiss)

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