Effects of nifedipine and Bay K 8644 on the R-PIA and caffeine-induced changes in the locomotor activity of rats

Abstract

Possible interaction between adenosine and L type Ca2+ channel in the locomotor activity of rats was investigated, R-PIA (0.05 mg kg(-1)), an adenosine analogue, (20 mg kg(-1)), an adenosine receptor antagonist, significantly decreased locomotor activity, respectively. Ca2+ channel blocker nifedipine (5 mg kg(-1)) and the channel activator Bay K 8644 (0.5 mg kg(-1)) did not alter the locomotor activity. However, both drugs significantly potentiated the inhibitory effect of R-PIA on the locomotor activity. Additionally, caffeine induced increase in the locomotor activity was significantly blocked by nifedipine and Bay K 8644, This interaction might be due to the inhibitory effects of nifedipine and Bay K 8644 on the uptake of adenosine by rat brain. (C) 1996 The Italian Pharmacological Society