Mechanism of NaCl secretion in rectal gland tubules of spiny dogfish (Squalus acanthias) . II. Effects of inhibitors
Greger, R.; Schlatter, E.
Pflugers Archiv European Journal of Physiology 402(4): 364-375
1984
ISSN/ISBN: 0031-6768 PMID: 6522244 Document Number: 221824
Rectal gland tubule (RGT) segments of the spiny dogfish (S. acanthias) were perfused in vitro. The effects of inhibitors of known mode of action on transepithelial PD potential difference , PDte resistance (Rte), the PD across the basolateral membrane (PDbl), the fractional resistance of this membrane (FRbl) and intracellular activities of Na+, Cl-, K+ (.alpha.cell) were examined. Furosemide (5 .cntdot. 10-4 mol .cntdot. l-1) reduced PDte from -12 .+-. 0.7 to -2.3 .+-. 0.2 mV (n = 63), hyperpolarized PDbl from -71 .+-. 1.3 to -79 .+-. 0.9 mV (n = 59), FRbl decreased from 0.2 .+-. 0.03 to 0.13 .+-. 0.01 (n = 21), .**GRAPHIC**. fell from 38 .+-. 4 to 11 .+-. 2 mmol .cntdot. l-1 (n = 14), .**GRAPHIC**. fell from 37 .+-. 4 to 17 .+-. 2 mmol .cntdot. l-1 (n = 12) and .**GRAPHIC**. was constant 113 .+-. 14 vs. 117 .+-. 15 mmol .cntdot. l-1 (n = 6) . Furosemide exerted its effects within some 20-40 s. Its action was completely reversible. Analysis of the time courses revealed that the furosemide induced initial fall in .**GRAPHIC**. was appr. twice as rapid when compared to that of .**GRAPHIC**. Ba2+ 0.5 mmol .cntdot. l-1 (bath) reduced PDte from -7.4 .+-. 1.2 to -4.1 .+-. 0.6 mV (n = 24), increased Rte from 18 .+-. 2 to 22 .+-. 2.5, .OMEGA.cm2 (n = 14). PDbl depolarized from -75 .+-. 2 to -48 .+-. 2 mV (n = 42), FRbl increased from 0.2 .+-. 0.02 to 0.34 .+-. 0.04 (n = 14) and .**GRAPHIC**. increased from 143 .+-. 28 to 188 .+-. 49 mmol .cntdot. l-1 (n = 4). Ouabain (50 .cntdot. 10-6 mmol .cntdot. l-1, bath) reduced PDte from -12 .+-. 2 to -3 .+-. 0.5 mV (n = 9), Rte increased from 18 .+-. 3 to 21 .+-. 3 .OMEGA.cm2 (n = 5), PDbl depolarized from -67 .+-. 4 to -26 .+-. 3 mV (n = 14), FRbl increased from 0.23 .+-. 0.04 to 0.45 .+-. 0.05 (n = 6), .**GRAPHIC**. fell only slightly from 135 .+-. 15 to 112 .+-. 30 mmol .cntdot. l-1 (n = 4), but .**GRAPHIC**. increased from 35 .+-. 12 to 111 .+-. 37 mmol .cntdot. l-1 (n = 3).