Lead effects on non-adrenergic non-cholinergic relaxations in the rat gastric fundus

The effect of lead exposure on non-adrenergic non-cholinergic (NANC) relaxations in rat gastric fundus was evaluated in this work. Wistar rats were divided into four groups: The control group received tap water and the three other received 0.008% of lead acetate in their drinking water for 15, 30 and 120 days. NANC relaxations induced by electrical field stimulation (0.5-8 Hz, 1 ms, 60 V) of gastric fundus strips was inhibited in all groups treated with lead. The strips from groups, control and 120 days of lead treatment (LEAD 120), were incubated with l-NOARG (100 μM). The presence of this blocker did not produce any additional inhibition. Sodium nitroprusside (10−10-10−6 M) and 8-Br-GMPc (3 × 10−8-3 × 10−4 M) produced dose-dependent relaxations in strips of both groups control and LEAD 120, however, in the LEAD 120, the potencies were significantly reduced from 7.32 ± 0.05 to 6.40 ± 0.09 (n = 5) and 4.26 ± 0.06 to 3.69 ± 0.05 (n = 5), respectively. Our data suggest that the chronic exposure to lead inhibits NANC relaxations probably by modulating NO release from NANC nerves and/or by interacting with intracellular transducer mechanisms in rat gastric fundus.