Effects of the carbonic anhydrase inhibitor acetazolamide on transmitter release at the mouse neuromuscular junction.

GROISMAN AI.; LINO NOELIA G.; UCHITEL OD.

Huerta Grande. Cordoba

Congreso; XXVII Congreso Anual de la Sociedad Argentina de Investigación en Neurociencias; 2012

Sociedad Argentina de Investigación en Neurociencias

Effects of the carbonic anhydrase inhibitor acetazolamide on transmitter release at the mouse neuromuscular junction. Ayelén I. Groisman, Noelia Lino, Osvaldo D. Uchitel Instituto de Fisiología, Biología Molecular y Neurociencias. CONICET. Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, UBA. ayelen.groisman@gmail.com Acetazolamide (AZ) is known to inhibit the action of carbonic anhydrase, an enzime responsible for regulating the extra- and intracellular pH (Maren T. H., 1967). This drug is used as an anticonvulsant and for treatment of episodic ataxia type-2 patients (Robbins et al., 2009), but its mechanism of action is still unknown. To gain insight on this subject, we studied the dynamics of stimulated vesicular exocytosis using fluorescence assays in ex vivo levator auris longus muscles. The drug was applied to the bath solution at a concentration of 100μM, which is found in the pharmacological range. Motor end-plates were loaded by stimulation of the neuromuscular junction (NMJ) at 20Hz in the presence of FM2-10 dye and, after washing, were unloaded at 50 Hz. Pictures were acquired every 3s for at least 700s. Unloaded control NMJ retained only a 16±2% of the initial fluorescence; in contrast, AZ treated NMJ retained 62±14%, suggesting that AZ affects the evoked induced exocytosis. Preliminary electrophysiological experiments performed in low Ca2+ and high Mg2+ solution showed, in agreement with the above results, a 58% increase in evoked end-plate potentials failures.