Determination of kainic acid-induced release of nitric oxide using a novel hemoglobin trapping technique with microdialysis.
We have demonstrated the usefulness of a novel hemoglobin-trapping technique to quantify nitric oxide (NO) concentrations in vivo. Concentric microdialysis probes were implanted into the hippocampus of rats under urethane anesthesia and perfused with 1 microM oxyhemoglobin in artificial CSF to sequester NO in extracellular fluid. The concentration of methemoglobin was then determined spectrophotometrically. The basal level of NO in hippocampus was 2.2 +/- 0.5 nM (in vitro sensitivity of the probe was 0.2 nM). Administration of 13 mg/kg, i.p., of kainic acid (KA) produced a maximal 5.3-fold increase at 100 min in NO levels (11.8 +/- 0.2 nM). This response was significantly attenuated by pretreatment with the NO synthase inhibitor N-monomethyl-L-arginine (50 mg/kg, 30 min before KA). These results demonstrate that a microdialysis probe using a novel hemoglobin-trapping technique possesses adequate sensitivity to determine the basal levels of NO and document the ability of KA to increase these levels via a NO synthase-mediated mechanism.
Balcioglu
A
A
Department of Pharmacology, Massachusetts College of Pharmacy and Allied Health Sciences, Boston 02115.
Maher
T J
TJ
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D007608:Kainic Acid / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D017551:Microdialysis / Q000379:methods; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism*; D010108:Oxyhemoglobins; D051381:Rats; D013997:Time Factors; D019323:omega-N-Methylarginine
D010108:Oxyhemoglobins; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; D007608:Kainic Acid