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Titolo:
OSMOTIC GRADIENT-INDUCED WATER PERMEATION ACROSS THE SARCOLEMMA OF RABBIT VENTRICULAR MYOCYTES
Autore:
SULEYMANIAN MA; BAUMGARTEN CM;
Indirizzi:
VIRGINIA COMMONWEALTH UNIV,MED COLL VIRGINIA,DEPT PHYSIOL RICHMOND VA23298 VIRGINIA COMMONWEALTH UNIV,MED COLL VIRGINIA,DEPT PHYSIOL RICHMOND VA23298
Titolo Testata:
The Journal of general physiology
fascicolo: 4, volume: 107, anno: 1996,
pagine: 503 - 514
SICI:
0022-1295(1996)107:4<503:OGWPAT>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
ATRIAL-NATRIURETIC-FACTOR; CELL CHIP28 PROTEIN; LIPID-MEMBRANES; XENOPUS OOCYTES; PERMEABILITY; VOLUME; CHANNEL; RECONSTITUTION; EXPRESSION; DECREASE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
55
Recensione:
Indirizzi per estratti:
Citazione:
M.A. Suleymanian e C.M. Baumgarten, "OSMOTIC GRADIENT-INDUCED WATER PERMEATION ACROSS THE SARCOLEMMA OF RABBIT VENTRICULAR MYOCYTES", The Journal of general physiology, 107(4), 1996, pp. 503-514

Abstract

The mechanism of water permeation across the sarcolemma was characterized by examining the kinetics and temperature dependence of osmotic swelling and shrinkage of rabbit ventricular myocytes. The magnitude ofswelling and the kinetics of swelling and shrinkage were temperature dependent, but the magnitude of shrinkage was very similar at 6 degrees, 22 degrees, and 37 degrees C. Membrane hydraulic conductivity, L(p)was similar to 1.2 x 10(-10) liter . N-1. s(-1) at 22 degrees C, corresponding to an osmotic permeability coefficient, P-f, of 16 mu m . s(-1), and was independent of the direction of water flux, the magnitudeof the imposed osmotic gradient (35-165 mosm/liter), and the initial cell volume. This value of L(p) represents an upper limit because the membrane was assumed to be a smooth surface. Based on capacitive membrane area, L(p) was 0.7 to 0.9 x 10(-10) liter . N-1. s(-1). Nevertheless, estimates of L(p) in ventricle are 15 to 25 times lower than thosein human erythrocytes and are in the range of values reported for protein-free lipid bilayers and biological membranes without functioning water channels (aquaporin). Evaluation of the effect of unstirred layers showed that in the worst case they decrease L(p) by less than or equal to 2.3%. Analysis of the temperature dependence of L(p) indicated that its apparent Arrhenius activation energy, E(a)('), was 11.7 +/- 0.9 kcal/mol between 6 degrees and 22 degrees C and 9.2 +/- 0.9 kcal/mol between 22 degrees and 37 degrees C. These values are significantly greater than that typically found for water flow through water-filled pores, similar to 4 kcal/mol, and are in the range reported for artificial and natural membranes without functioning water channels. Taken together, these data strongly argue that the vast majority of osmotic water flux in ventricular myocytes penetrates the lipid bilayer itself rather than passing through water-filled pores.

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Documento generato il 27/10/20 alle ore 10:37:25