Nitric oxide produces different actions in different areas of the periaqueductal grey in cats.
In 20 urethane-anaesthetised cats, microinjection of N-methyl-D-aspartate (NMDA) into the intermediate-lateral (IL-) or the dorsolateral (DL-) periaqueductal grey areas (PAG) of the midbrain elicited similar patterns of cardiovascular responses: increases in mean systemic arterial pressure (MSAP), heart rate (HR) and mean blood flows (F) of the common carotid and femoral arteries, accompanied with a 'hissing-howling' response. Similar increases in MSAP and Fs were induced by microinjections of S-nitroso-N-acetylpenicillamine (SNAP), a potent nitric oxide (NO) donor, on the IL-PAG (A2.5-A0.5). In contrast, microinjections of N(G)-nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor, in the same area elicited a decrease in MSAP and Fs. On the other hand, microinjections of either SNAP or L-NAME reversed the original IL-PAG responses when injected into the DL-PAG. Pretreatments with SNAP significantly inhibited NMDA-induced responses in the DL-PAG but potentiated such responses in the IL-PAG. In contrast, pretreatments with L-NAME potentiated the NMDA-induced responses in the DL-PAG but inhibited such responses in the IL-PAG. These data suggest that NO may be a neurotransmitter or neuromodulator that exerts differential function in different defense areas, namely the IL- and the DL-PAG.
Wang
M R
MR
Graduate Institute of Life Science, National Defense Medical Center, Taiwan, Republic of., Taipei, China.
Kuo
J S
JS
Chai
C Y
CY
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002320:Cardiovascular Physiological Phenomena / Q000187:drug effects*; D002415:Cats / Q000033:anatomy & histology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D010487:Periaqueductal Gray / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D026423:S-Nitroso-N-Acetylpenicillamine; D014828:Vocalization, Animal / Q000187:drug effects / Q000502:physiology*
D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D009569:Nitric Oxide; D026423:S-Nitroso-N-Acetylpenicillamine; D019001:Nitric Oxide Synthase; D010396:Penicillamine; D019331:NG-Nitroarginine Methyl Ester