Electrogenic Cation Transport Across Leech Caecal Epithelium

Overview

Journal J Comp Physiol B

Specialties Biochemistry
Endocrinology
Physiology

Date 1996 Jan 1

PMID 8956504

Authors

H Milde

W Clauss

W M Weber

Affiliations

Soon will be listed here.

Abstract

Electrogenic cation transport across the caecal epithelium of the leech Hirudo medicinalis was investigated using modified Ussing chambers. Transepithelial resistance (RT) and potential difference (VT) were 61.0 +/- 3.5 omega.cm2 and -1.1 +/- 0.2 mV (n = 149), respectively, indicating that leech caecal epithelium is a "leaky" epithelium. Under control conditions short circuit current (ISC) and transepithelial Na+ transport rate (INa) averaged at 22.1 +/- 1.5 microA.cm-2 and 49.7 +/- 2.6 microA.cm-2, respectively. Mucosal application of amiloride (100 mumol.l-1) or benzamil (50 mumol.l-1) influenced neither ISC nor INa. The transport system in the apical membrane showed no pronounced cation selectivity and a linear dependence on mucosal Na+ concentration. Removal of mucosal Ca2+ increased ISC by about 50% due to an increase of transepithelial Na+ transport. Trivalent cations (La3+ and Tb3+, 1 mmol.l-1 both) added to the mucosal Ringer solution reduced INa by more than 40%. Serosal ouabain (1 mmol.l-1) almost halved ISC and INa while 0.1% (= 5.4 mmol.l-1) DNP decreased INa to 11.8 +/- 5.1% of initial values. Serosal addition of cAMP increased both ISC and INa whereas the neurotransmitters. FMRFamide, acetylcholine, GABA, L-dopa, serotonin and dopamine failed to show any effects; octopamine, glycine and L-glutamate reduced INa markedly. On the basis of these results we conclude that in leech caecal epithelium apical uptake of monovalent cations is mediated by non-selective cation conductances which are sensitive to extracellular Ca2+ but insensitive to amiloride. Basolaterally Na+ is extruded via ouabain-sensitive and -insensitive ATPases. cAMP activates Na+ transport across leech caecal epithelium, although the physiological stimulus for cAMP-production remains unknown.

References

Evans B, Pohl J, Kartsonis N, Calabrese R . Identification of RFamide neuropeptides in the medicinal leech. Peptides. 1991; 12(5):897-908. DOI: 10.1016/0196-9781(91)90035-n. View

Fromter E . The route of passive ion movement through the epithelium of Necturus gallbladder. J Membr Biol. 1972; 8(3):259-301. DOI: 10.1007/BF01868106. View

Van Driessche W, Lindemann B . Low-noise amplification of voltage and current fluctuations arising in epithelia. Rev Sci Instrum. 1978; 49(1):52. DOI: 10.1063/1.1135251. View

Salzet M, Bulet P, Wattez C, Malecha J . FMRFamide-related peptides in the sex segmental ganglia of the Pharyngobdellid leech Erpobdella octoculata. Identification and involvement in the control of hydric balance. Eur J Biochem. 1994; 221(1):269-75. DOI: 10.1111/j.1432-1033.1994.tb18738.x. View

Cox T . Calcium channel blockers inhibit amiloride-stimulated short-circuit current in frog tadpole skin. Am J Physiol. 1992; 263(4 Pt 2):R827-33. DOI: 10.1152/ajpregu.1992.263.4.R827. View

Wenning A, Cahill M, Hoeger U, Calabrese R . Sensory and neurosecretory innervation of leech nephridia is accomplished by a single neurone containing FMRFamide. J Exp Biol. 1993; 182:81-96. DOI: 10.1242/jeb.182.1.81. View

Cremaschi D, Porta C . Sodium salt neutral entry at the apical membrane of the gallbladder epithelium: comparing different species. Comp Biochem Physiol Comp Physiol. 1992; 103(4):619-33. DOI: 10.1016/0300-9629(92)90157-l. View

Van Driessche W, Desmedt L, Simaels J . Blockage of Na+ currents through poorly selective cation channels in the apical membrane of frog skin and toad urinary bladder. Pflugers Arch. 1991; 418(3):193-203. DOI: 10.1007/BF00370514. View

Reuss L . Ion transport across gallbladder epithelium. Physiol Rev. 1989; 69(2):503-45. DOI: 10.1152/physrev.1989.69.2.503. View

10.

Sellin J, Dubinsky W . Apical nonspecific cation conductances in rabbit cecum. Am J Physiol. 1994; 266(3 Pt 1):G475-84. DOI: 10.1152/ajpgi.1994.266.3.G475. View

11.

Heming T, Copello J, Reuss L . Regulation of cAMP-activated apical membrane chloride conductance in gallbladder epithelium. J Gen Physiol. 1994; 103(1):1-18. PMC: 2216856. DOI: 10.1085/jgp.103.1.1. View

12.

Van Driessche W, Zeiske W . Ca2+-sensitive, spontaneously fluctuating, cation channels in the apical membrane of the adult frog skin epithelium. Pflugers Arch. 1985; 405(3):250-9. DOI: 10.1007/BF00582569. View

13.

Krattenmacher R, Voigt R, Clauss W . Ca-sensitive sodium absorption in the colon of Xenopus laevis. J Comp Physiol B. 1990; 160(2):161-5. DOI: 10.1007/BF00300948. View

14.

Aelvoet I, Erlij D, Van Driessche W . Activation and blockage of a calcium-sensitive cation-selective pathway in the apical membrane of toad urinary bladder. J Physiol. 1988; 398:555-74. PMC: 1191787. DOI: 10.1113/jphysiol.1988.sp017057. View

15.

Weber W, Dannenmaier B, Clauss W . Ion transport across leech integument. I. Electrogenic Na+ transport and current fluctuation analysis of the apical Na+ channel. J Comp Physiol B. 1993; 163(2):153-9. DOI: 10.1007/BF00263601. View

16.

Lindemann B . Fluctuation analysis of sodium channels in epithelia. Annu Rev Physiol. 1984; 46:497-515. DOI: 10.1146/annurev.ph.46.030184.002433. View

17.

Nicholls J, KUFFLER S . EXTRACELLULAR SPACE AS A PATHWAY FOR EXCHANGE BETWEEN BLOOD AND NEURONS IN THE CENTRAL NERVOUS SYSTEM OF THE LEECH: IONIC COMPOSITION OF GLIAL CELLS AND NEURONS. J Neurophysiol. 1964; 27:645-71. DOI: 10.1152/jn.1964.27.4.645. View

18.

OConnor S . Recent developments in the classification and functional significance of receptors for ATP and UTP, evidence for nucleotide receptors. Life Sci. 1992; 50(22):1657-64. DOI: 10.1016/0024-3205(92)90420-t. View

19.

Weber W, Blank U, Clauss W . Regulation of electrogenic Na+ transport across leech skin. Am J Physiol. 1995; 268(3 Pt 2):R605-13. DOI: 10.1152/ajpregu.1995.268.3.R605. View

20.

Heinz M, Krattenmacher R, Hoffmann B, Clauss W . Different modes of electrogenic Na+ absorption in the coprodeum of the chicken embryo: role of extracellular Ca2+. J Comp Physiol B. 1991; 161(4):363-70. DOI: 10.1007/BF00260794. View