Resumo

CASTELLANOS, Jessika  e  EBLEN-ZAJJUR, Antonio. Digoxine reduces thermal pain threshold and neuromuscular coordination in rats. AVFT [online]. 2015, vol.34, n.2, pp.23-26. ISSN 0798-0264.

It is well known that inhibition of Na,K-ATPase by digoxine induces an increased [Na⁺]_i and [Ca⁺⁺]_i with consequent increased cell depolarization. This effect has a potential implication on nociception. To analyze this digoxine effect on pain threshold and neuromuscular activity, 20 male Sprague-Dawley rats (~300gr) were treated with NaCl 1mL, 0.9% (Controls, n=10) or digoxine 1mL, 40 μg.Kg^-1.day^-1 (Digoxine, n=10) i.p. for a week. Daily test was performed for pain threshold by hot plate test (50±0.1ºC, mean±SEM) and neuromuscular motor coordination by rotarod test (at 17 rpm). Digoxine reduced 28% the hot plate latency (17.16±2.05s) when compared to controls (23.83±2.32s; P<0,001) and reduces neuromuscular activity in 95.4% (1.02±5.42s digoxine vs 22.22±5.50s; P<0.001). Both effects were observed from the first doses. There was no correlation neither between hotplate and rotarod tests latencies nor between these values and the accumulative doses of digoxine. These results strongly suggest the pronociceptive effect of digoxine by decrease of the thermal pain threshold and that this could be more intense than reported due to the masking effect of a reduced motor activity during behavioral tests. The present results contribute to explain recent report of increased pain in digoxine treated human patients.

Palavras-chave : Digoxine; Na; K-ATPase; Pain threshold; Hot plate test; Rotarod test.