Transepithelial short circuit currents in human and porcine isolated ciliary bodies: effect of acetazolamide and epinephrine.

BACKGROUND

To investigate in human and porcine isolated ciliary bodies the effect of acetazolamide and epinephrine on ciliary transepithelial ionic currents (a parameter linked to aqueous humor production).

MATERIAL AND

METHODS

Isolated ciliary bodies were mounted in a Ussing-type chamber to measure transepithelial potential difference (PD) and short circuit current (Isc) before and after exposure to either 100 micro M acetazolamide or 10 micro M epinephrine.

RESULTS

In humans (N = 27), baseline PD was 1184 +/- 100 micro V (negative on the non-pigmented epithelial [NPE] side) and Isc 19.9 +/- 1.5 micro A/cm 2. Acetazolamide (N = 7 - 8) decreased Isc (NPE side: 8.4 +/- 1.1 micro A/cm 2; pigmented epithelial [PE] side: 7.4 +/- 0.9 micro A/cm 2) while epinephrine (N = 6) increased Isc only on the NPE side (9.9 +/- 0.8 micro A/cm 2). In pigs, baseline PD was in some preparations negative (862 +/- 84 micro V, N = 18) and in others positive (814 +/- 81 micro V, N = 10) on the NPE side with Isc 15.6 +/- 1.6 micro A/cm 2 and 16.3 +/- 2.6 micro A/cm 2, respectively. In all preparations, acetazolamide (N = 6 - 7) decreased Isc (NPE side: 6.1 +/- 0.6 micro A/cm 2; PE side: 4.8 +/- 0.3 micro A/cm 2) while epinephrine (N = 8) increased it only on the NPE side (10.5 +/- 0.6 micro A/cm 2).

CONCLUSIONS

To our knowledge, this is the first time that this methodology is applied to measure transepithelial ionic currents in isolated human and porcine ciliary bodies. This method could be used to test drugs modulating aqueous humor production.