Nitric oxide-dependent mitotic activity in salivary glands of the rat upon sympathetic stimulation.
Incorporation of [3H]thymidine into trichloroacetic acid (TCA)-insoluble material of the parotid and submandibular glands was used as an index of mitotic activity following unilateral electrical stimulation of the sympathetic innervation (20 Hz, 4 min every fifth minute over 34 min). Stimulation under beta-adrenoceptor blockade (propranolol 2 mg/kg, intravenous) alone or combined with alpha-adrenoceptor blockade (phentolamine 2 mg/kg, intravenous) did not increase the rate of [3H]thymidine incorporation into the two types of glands. However, under alpha-adrenoceptor blockade the [3H]thymidine incorporation increased into the parotid glands, by 122% (compared to the glands on the contralateral side), but not into the submandibular glands. In the presence of the neuronal type NO-synthase (nNOS) blocker N-PLA (30 mg/kg, intravenous) or the unselective NO-synthase blocker L-NAME (30 mg/kg, intravenous), this increase was reduced to 49 and 47%, respectively. Thus, the major part of the sympathetically nerve-evoked beta-adrenoceptor-mediated mitotic response was found to depend on the activity of neuronal type NO-synthase to generate NO. Since the sympathetic nerve fibres of the parotid gland lack NO-synthase, the neuronal type NO-synthase subjected to the inhibitors is likely to be of parenchymal origin.
Ekström
J
J
Department of Pharmacology, Sahlgrenska Academy at Göteborg University, Medicinaregatan 15 D, PO Box 431, Göteborg 413 90, Sweden. jorgen.ekstrom@pharm.gu.se
Sayardoust
Shariel
S
Cevik
Hülya
H
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D005260:Female; D008938:Mitosis / Q000187:drug effects / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D010306:Parotid Gland / Q000166:cytology / Q000187:drug effects / Q000294:innervation; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012469:Salivary Glands / Q000166:cytology* / Q000187:drug effects / Q000294:innervation; D013363:Submandibular Gland / Q000166:cytology / Q000187:drug effects / Q000294:innervation; D013564:Sympathetic Nervous System / Q000502:physiology*
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D009569:Nitric Oxide; D011433:Propranolol; D010646:Phentolamine