Nitric oxide donor sodium nitroprusside inhibits the acetylcholine-induced K+ current in identified Aplysia neurons

✍ Scribed by M. Sawada; M. Ichinose

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 668 KB
• Volume: 44
• Category: Article
• ISSN: 0360-4012
• DOI: 10.1002/(sici)1097-4547(19960401)44:1<21::aid-jnr3>3.0.co;2-k

✦ Synopsis

The effects of bath-applied sodium nitroprusside (SNP), a nitric oxide (NO) donor, on an acetylcholine (ACh)-induced K+ current recorded from identified neurons (R9 and R10) of Aplysia kurodui were investigated with conventional voltage-clamp and pressure ejection techniques. Bath-applied SNP (25-50 pM) reduced the ACh-induced K+ current in the neurons without affecting the resting membrane conductance and holding current. The suppressing effects of SNP on the current were completely reversible. Intracellular injection of 1 mM guanosine 3',5'-cyclic monophosphate (cGMP) or bath-applied 50 pM 3-isobutyl-1-methylxanthine (IBMX), a nonspecific phosphodiesterase (PDE) inhibitor, also inhibited the ACh-induced current, thus mimicking the effect of the NO donor on the ACh-induced current. In contrast, pretreatment with methylene blue (10 pM), an inhibitor of guanylate cyclase, and hemoglobin (50 pM), a nitric oxide scavenger, decreased the SNPinduced inhibition of the ACh-induced current. These results suggest that SNP, a NO donor, inhibits the ACh-induced K+ current, and that the mechanism of NO inhibition of the ACh-induced current recorded from identified ApZysiu neurons involves cGMP-dependent protein kinase.