Histamine and acetylcholine regulation of sympathetic nerve activity in guinea-pig nasal mucosa

Abstract

The regulating effects of histamine and acetylcholine (Ach) in norepinephrine (NE) transmission in nasal mucosa were investigated by analyzing 3H-NE release from isolated guinea-pig tissues. In addition, localization of the histamine H1 receptor and the muscarinic acetylcholine receptor on the sympathetic nerve in the guinea-pig nasal mucosa were examined by quantitatively evaluating these receptors after the unilateral removal of the superior cervical ganglion. Ach inhibited electrically-stimulated 3H-NE release in a concentration-dependent manner, and this effect was blocked by atropine. Histamine inhibited electrically-induced 3H-NE release at a concentration of 10(-5) M but enhanced it in concentration of 10(-3) M. Histamine increased the spontaneous release of 3H-NE in a dose-dependent manner, which was inhibited by pyrilamine (H1 antagonist) and excess Ach, but was not altered by cimetidine (H2 antagonist). These results suggest the following: 1) Local regulation of NE transmission in nasal mucosa involved excitatory H1 receptors, inhibitory H2 receptors and inhibitory muscarine receptors which can be facilitated by sensory stimulation with histamine. 2) Histamine regulation may vary with a balance between the excitatory and inhibitory effects. 3) Histamine in the high concentrations seen in cases of nasal allergy, may shift this balance causing increased NE release; at low concentrations, NE release is inhibited. In the second series of this study, we were unable to demonstrate a decreased number of either H1 or muscarine receptors on the side affected by unilateral cervical ganglia sympathectomy.