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Titolo:
BIOELECTRIC PROPERTIES OF PROXIMAL BRONCHIOLAR EPITHELIUM
Autore:
BALLARD ST; TAYLOR AE;
Indirizzi:
UNIV SO ALABAMA,COLL MED,DEPT PHYSIOL,MSB 3024 MOBILE AL 36688
Titolo Testata:
The American journal of physiology
fascicolo: 1, volume: 267, anno: 1994,
parte:, 1
pagine: 120000079 - 120000084
SICI:
0002-9513(1994)267:1<120000079:BPOPBE>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
DOG TRACHEAL EPITHELIUM; ION-TRANSPORT; AIRWAY EPITHELIUM; CLARA CELLS; NA+; CL; INVITRO; FLOW;
Keywords:
BRONCHIOLES; CYSTIC FIBROSIS; SODIUM ABSORPTION; CHLORIDE SECRETION; EPITHELIAL TRANSPORT; SHORT-CIRCUIT CURRENT; RESISTANCE; TRANSEPITHELIAL POTENTIAL DIFFERENCE; PIGS; SMALL AIRWAYS; AMILORIDE; BUMETANIDE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
22
Recensione:
Indirizzi per estratti:
Citazione:
S.T. Ballard e A.E. Taylor, "BIOELECTRIC PROPERTIES OF PROXIMAL BRONCHIOLAR EPITHELIUM", The American journal of physiology, 267(1), 1994, pp. 120000079-120000084

Abstract

Distal airway epithelium is widely believed to secrete ions and liquid into the airspace, although this process has never been demonstratedin intact small airways. To determine the characteristics of active ion transport in distal airway epithelium, the effects of selective inhibitors of active Na+ absorption and Cl- secretion on the bioelectric properties of intact proximal bronchiolar epithelium were evaluated. Large bronchioles (450-1,200 mu m outside diameter, 1.5-5.0 mm length) were excised from 4- to 8-wk-old pigs, cannulated with glass microcannulas, and perfused. Transepithelial potential difference (PD), short-circuit current (I-sc), and resistance (R(m)) were measured by cable analysis. In 14 tissues, resting PD, I-sc, and R(m) were -3.4 +/- 0.4 mV(lumen negative), 19.6 +/- 4.7 mu A/cm(2), and 255 +/- 50 Ohm.m2, respectively. The conductive Na+ channel blocker amiloride (10 mu M) significantly (P < 0.05) reduced PD and I-sc by 37 and 41% and significantly increased R(m) by 23% in seven tissues. Subsequent bumetanide (10 mu M), a blocker of active Cl- secretion through inhibition of Na+-K+-2Cl(-) cotransport, significantly reduced the amiloride-insensitive PD and I-sc by 41 and 50%, whereas R(m) significantly increased 15%. Because amiloride is known to induce Cl- secretion, the order of drug addition was reversed to determine the fractional contribution of active Cl- secretion to the resting PD, I-sc, and R(m). In seven different bronchioles, bumetanide did not significantly affect PD, I-sc, or R(m). However, subsequent amiloride significantly reduced PD and I-sc to 38 and 31% of control values, and R(m) was significantly increased 16%. These data demonstrate that active Na+ absorption accounts for most of the resting I-sc in proximal porcine bronchioles. Little if any active Cl- secretion occurs under basal conditions, but secretion of this ionis induced by amiloride. If we assume that electroneutral ion secretion is absent or minimal in this tissue, the principal ionic driving force for liquid movement across proximal bronchioles under basal, unstimulated conditions is absorptive.

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Documento generato il 07/07/20 alle ore 12:33:56