NITRERGIC NEURONS IN THE CANINE INTRINSIC LARYNGEAL MUSCLE

Nitrergic ganglionic cells located in the canine intrinsic laryngeal m uscle were studied by NADPH-diaphorase (NADPH-d) histochemistry and ne uronal nitric oxide synthase (nNOS) immunohistochemistry. Cells intens ely stained by NADPH-d histochemistry were found between the striated muscle fibers of the intrinsic laryngeal muscle. Most of these cells w ere bipolar or pseudounipolar in form. Some NADPH-d negative cells wer e observed to be enveloped in a mesh by varicose NADPH-d positive nerv e fibers. The findings obtained by nNOS immunohistochemistry correspon ded well with those obtained by NADPH-d histochemistry, indicating tha t NADPH-d activity in the ganglion in the intrinsic laryngeal muscle i s nNOS. The present findings clearly indicate that some of the ganglio n cells located in the canine intrinsic laryngeal muscle are nitrergic , and that the ganglionic cells synapse together with the participatio n of nitric oxide in integrating ganglionic cells.