PULMONARY SEROTONIN 5-HT3-SENSITIVE AFFERENT-FIBERS MODULATE RENAL SYMPATHETIC-NERVE ACTIVITY IN RATS

Citation
R. Veelken et al., PULMONARY SEROTONIN 5-HT3-SENSITIVE AFFERENT-FIBERS MODULATE RENAL SYMPATHETIC-NERVE ACTIVITY IN RATS, American journal of physiology. Heart and circulatory physiology, 41(2), 1997, pp. 979-986
Citations number
38
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physiology
ISSN journal
0363-6135
Volume
41
Issue
2
Year of publication
1997
Pages
979 - 986
Database
ISI
SICI code
0363-6135(1997)41:2<979:PS5AMR>2.0.ZU;2-J
Abstract
Cardiopulmonary reflexes with vagal afferents may control volume homeo stasis by influencing renal nerve activity. Such reflexes can be stimu lated mechanically and chemically, e.g., by serotonin (5-HT). We have demonstrated that stimulation of epicardial 5-HT3 receptors inhibits r enal sympathetic nerve activity (RSNA) by a cardiorenal reflex. We now tested the hypothesis that pulmonary 5-HT3-sensitive vagal afferent f ibers participate in the control of renal nerve activity. Two sets of experiments were performed. First, the responses of multifiber RSNA, h eart rate (HR), and blood pressure (BP) to the 5-HT3-receptor agonist phenylbiguanide (PEG; 10 mu g iv) were recorded in the presence of int act pulmonary afferents. Abdominal afferents were removed by subdiaphr agmatic vagotomy. Cardiac afferents were blocked by intrapericardial i njection of 10% procaine. Second, the responses of 25 single vagal pul monary afferent C fibers to PEG were assessed. PEG decreased BP, HR, a nd RSNA (-90 +/- 8%). When cardiac afferents were blocked by procaine, BP and HR failed to decrease in response to PEG; however, the RSNA de crease was still -48 +/- 8%. Single fibers generally responded to PEG by a slight increase in firing rate. A distinct subset of fibers (5 of 25) showed an activity increase of >15 Hz that preceded changes in BP and HR. The decreased RSNA in the absence of cardiac and abdominal va gal afferents and the strong response of 20% of pulmonary single fiber s to intravenous PEG suggest that pulmonary fibers play a role in a 5- HT3 serotenergic reflex. Thus pulmonary serotonin could influence the neural control of renal function.