Cyclic AMP and anionic currents in porcine ciliary epithelium.

INTRODUCTION

To investigate whether in the ciliary epithelium of isolated porcine ciliary body cyclic 3',5' adenosine monophosphate (cAMP) activates transmembrane anionic currents.

METHODS

Changes in membrane potential induced either by the adenylcyclase activator forskolin (10 microM; n = 4) or the stable membrane permeable cAMP analog 8-bromo-adenosine 3',5'-cyclic monophosphothioate (8-br-cAMP; 30 microM; n = 4) were measured with intracellular microelectrodes. The effect of the drugs were assessed in the absence or in the presence of the non-selective anionic channel/transporter inhibitor diisothiocyanatostilbene-2,2' disulfonic acid (DIDS; 1 mM; n = 4).

RESULTS

Significant (p < 0.001) membrane potential depolarization were induced by both forskolin (11.8 +/- 0.3 mV) or 8-br-cAMP (9.3 +/- 0.4 mV). In the presence of DIDS, a significant (p < 0.001) inhibition of the depolarization evoked by forskolin (0.9 +/- 1.1 mV) and 8-bromo-cAMP (0.7 +/- 0.2 mV) was observed.

CONCLUSIONS

In the ciliary epithelium of isolated porcine ciliary body cAMP induces membrane potential depolarization through a process that could involve anionic channels.