Transport Processes, Metabolism and Endocrinology; Kidney, Gastrointestinal Tract, and Exocrine Glands

Pflügers Archiv

, Volume 394, Issue 4, pp 287-293

First online:

Poorly selective cation channels in the skin of the larval frog (Stage≤XIX)

  • Stanley D. HillyardAffiliated withLaboratorium voor Fysiologie, K.U.L.
  • , Wolfgang ZeiskeAffiliated withLaboratorium voor Fysiologie, K.U.L.
  • , Willy Van DriesscheAffiliated withLaboratorium voor Fysiologie, K.U.L.

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access


The abdominal skin of bullfrog larvae (Rana catesbeiana) was placed in an Ussing-type chamber, and its transepithelial electrical parameters were recorded with mucosal solutions of different ionic composition. With “K+-like” cations (K+, NH 4 + , Rb+, Cs) the power spectra of the fluctuations in short-circuit current displayed a Lorentzian component (f c =30–40 Hz). The relaxation noise could be suppressed by addition of the K+-channel blockers Ba2+ and TEA to the mucosal solution. Also, in presence of the ionophore antibiotic nystatin the Lorentzian noise was abolished. The Na+-channel probes amiloride and benzimidazolyl-2-guanidine (BIG) both enhanced the relaxation noise obtained with the K+-like cations but, with Na+, and Li+, also caused the rise of a relaxation component above the background noise. In presence of amiloride or BIG, the addition of Ba2+, TEA and nystatin still abolished the Lorentzian noise. It can be concluded that the relaxation-noise source is located in the apical cell membranes of the tadpole skin. These spontaneously fluctuating cation channels do not seem to strictly discriminate between K+-like ions (K+, NH 4 + , Rb+, Cs+) and Na+-like ions (Na+, Li+). On the other hand, well-known specific probes for K+ channels (Ba2+, TEA) and for Na+ channels (amiloride, BIG) interact with this apical cation channel. It is possible that the poorly selective channel plays a role in the ontogenesis of the specific Na+ transport in the maturing frog skin.

Key words

Noise analysis Tadpole skin Apical membrane Cation channel Barium TEA (Tetraethyl ammonium) Amiloride