Regulation of goby intestinal ion absorption by the calcium messenger system

Loretz, Christopher A.

doi:10.1002/jez.1402440109

Cited by 10 publications

(2 citation statements)

References 26 publications

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“…Correspondingly, in flounder intestine, H-8 reversed the inhibitory effect of cyclic GMP but not that of Ca a+ ionophore (O'Grady et al 1988). In the goby intestine, consistent with such a scheme, [Ca2+]i acting through calmodulin inhibits NaC1 cotransport (Loretz 1987;Fig. 6).…”

Section: Ymentioning

confidence: 73%

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Inhibition of goby posterior intestinal NaCl absorption by natriuretic peptides and by cardiac extracts

Loretz

1996

J Comp Physiol B

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Natriuretic peptides abolish active Na+ and Cl- absorption across the posterior intestine of the euryhaline goby Gillichthys mirabilis. Inhibition by eel and human natriuretic peptides is dose-dependent with the following sequence of potencies based on experimentally determined ID50 values for inhibition of short-circuit current: eel ventricular natriuretic peptide (78 nmol.l-1), eel atrial natriuretic peptide (156 nmol.l-1), human brain natriuretic peptide (326 nmol.l-1), human alpha atrial natriuretic peptide (1.05 mumol.l-1), and eel C-type natriuretic peptide (75 mumol.l-1). Natriuretic peptides also significantly increase transcellular conductance. The observed sequence of natriuretic peptide potencies is suggestive of cellular mediation by GC-A-type NP-R1 receptors in this tissue; as expected for guanylyl-cyclase-coupled NP-R1 receptors, cyclic GMP mimics the action of natriuretic peptides on the goby intestine. Crude aqueous extracts of goby atrium and ventricle inhibited short circuit current and increased tissue conductance in a dose-dependent manner. Ventricular extract was more potent than atrial extract on both a per organ and per milligram basis.

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Section: Ymentioning

confidence: 73%

“…The specific methodology for the determination of short-circuit current (I~, the current required to reduce the transepithlial potential to 0mV, in gA.cm -z) and of transepithelial resistance (Rr, in f~" cm 2) and conductance (G~r, in mS. cm-2) have been published in detail elsewhere (Loretz 1983(Loretz , 1987.…”

Section: Electrophysiologymentioning

confidence: 99%

Inhibition of goby posterior intestinal NaCl absorption by natriuretic peptides and by cardiac extracts

Loretz

1996

J Comp Physiol B

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Recognition by goby intestine of a somatostatin analog, SMS 201-995

Loretz

1990

J. Exp. Zool.

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The caudal neurosecretory peptide urotensin I1 and its partial structural analog the hypothalamic and gastroenteropancreatic peptide somatostatin can be distinguished by the goby posterior intestine; urotensin I1 stimulates Na+ and C1-absorption whereas somatostatin is without effect. SandostatinR (Sandoz compound SMS 201-995) is a partial structural analog of somatostatin, possessing the active core common to both urotensin I1 and somatostatin but lacking the C-and N-terminal tails which apparently confer recognition in species specificity. SMS 201-995 mimicked the effects of urotensin 11, namely, increased net C1-absorption and decreased radiochloride backflux consistent with the observed increase in transepithelial resistance and the cellular depolarization typical of transport stimulation in this tissue. Speculation on the role of the tails in species-specific recognition is supported by the nature of amino acid residue substitutions in urotensin 11, somatostatin, and SMS 201-995 and suggests the existence of multiple receptor types for this group of peptides.

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Ion transport in the intestine of Gobius niger in both isotonic and hypotonic conditions

2003

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Ion transport in the intestine of Gobius niger, a euryhaline teleost, was studied in both isotonic and hypotonic conditions. Isolated tissues, mounted in Ussing chambers and bilaterally perfused with isotonic Ringer solution, developed a serosa negative transepithelial voltage and a short circuit current indicating a net negative current in absorptive direction. Bilateral removal of Cl À and Na þ from the bathing solutions as well as the luminal removal of K þ in the presence of Ba 2þ (10 À3 M) almost abolished both V t and I sc . Similar results were obtained by adding bumetanide (10 À5 M) to the luminal bath while other inhibitors of Cl À transport mechanisms were ineffective. These observations suggest that salt absorption begins with a coupled entry of Na þ , Cl À , and K þ across the apical membrane; a Ba 2þ inhibitable K þ conductance, demonstrated also by micropuncture experiments, recycles the ion into the lumen. Salt entry into the cell is driven by the operation of the basolateral Na þ /K þ -ATPase since serosal ouabain (10 À4 M) completely abolished both V t and I sc ; this pump also completes the Na þ absorption. The inhibitory effect of both serosal bumetanide (10 À4 M) and SITS (5?10 À4 M) suggests that Cl À would leave the cell via the KCl cotransport, the Cl/HCO 3 À antiport and/or conductive pathways. Bilateral exposure of tissues to hypotonic media produced a reduction of both the transepithelial voltage and the short circuit current probably due to the activation of homeostatic ionic fluxes involved in cell volume regulation. The results of experiments with both isolated enterocytes and intestine exposed to hypotonic solution suggested that the recovery of cell volume, after the initial cell swelling, involves a parallel opening of K þ and Cl À channels to facilitate net solute and water effluxes from the cell.

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Regulation of goby intestinal ion absorption by the calcium messenger system

Cited by 10 publications

References 26 publications

Inhibition of goby posterior intestinal NaCl absorption by natriuretic peptides and by cardiac extracts

Inhibition of goby posterior intestinal NaCl absorption by natriuretic peptides and by cardiac extracts

Recognition by goby intestine of a somatostatin analog, SMS 201-995

Ion transport in the intestine of Gobius niger in both isotonic and hypotonic conditions

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