Elevation of the nasal mucosal surface temperature after warming of the feet occurs via a neural reflex.
OBJECTIVE
To evaluate in humans the mechanisms underlying the increase in nasal mucosal temperature following immersion of the feet in warm water (42 degrees C).


METHODS
The nasal mucosal temperature of subjects was measured whilst their feet were immersed in warm water.


RESULTS
The nasal mucosal temperature rose quickly on immersion and dissipated equally fast on removal of the feet from warm water. Intranasal lidocaine raised the mucosal temperature slightly after application, but also blocked the feet warming-induced increase in nasal mucosal temperature, suggesting a neural reflex. Whereas the cutaneous-nasal reflex stimulates a transient parasympathetic response, acetylcholine does not seem to contribute to the more prolonged increase in nasal mucosal temperature following immersion of the feet in warm water. Warming of the feet probably leads to a loss of alpha-sympathetic activity of nasal blood vessels and an increase in nasal mucosal temperature because application of phenoxybenzamine, an alpha-sympathetic blocking agent, to the nasal mucosa increased the nasal mucosal temperature.


CONCLUSIONS
Our data suggest that the increase in nasal mucosal temperature after warming of the feet is mediated by a neural reflex, which is caused by loss of sympathetic activity of the nasal vasculature and a possible additional contribution of a long-acting parasympathetic mediator.
Assanasen
Paraya
P
Section of Otolaryngology--Head and Neck Surgery, The Pritzker School of Medicine, The University of Chicago, Chicago, Illinois 60637, USA.
Baroody
Fuad M
FM
Haney
Lauran
L
deTineo
Marcy
M
Naureckas
Edward
E
Solway
Julian
J
Naclerio
Robert M
RM
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000328:Adult; D000779:Anesthetics, Local / Q000494:pharmacology; D016022:Case-Control Studies; D018680:Cholinergic Antagonists / Q000494:pharmacology; D018592:Cross-Over Studies; D005260:Female; D005528:Foot; D006358:Hot Temperature; D006801:Humans; D007101:Immersion; D009241:Ipratropium / Q000494:pharmacology; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D009297:Nasal Mucosa / Q000098:blood supply / Q000502:physiology*; D010643:Phenoxybenzamine / Q000494:pharmacology; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D012039:Regional Blood Flow; D012881:Skin Temperature / Q000502:physiology*; D013564:Sympathetic Nervous System / Q000187:drug effects; D014867:Water
D000317:Adrenergic alpha-Antagonists; D000779:Anesthetics, Local; D018680:Cholinergic Antagonists; D014867:Water; D010643:Phenoxybenzamine; D008012:Lidocaine; D009241:Ipratropium