Local action of exogenous nitric oxide (NO) on the skin blood flow of rock pigeons (Columba livia) is affected by acclimation and skin site

Abstract

SUMMARY We studied the blood flow over dorsal and abdominal, non-brooding patch skin of two groups of pigeons: one group was thermally acclimated to cold(winter-acclimatized, WAC) while the other group was acclimated to a mesic environment (thermally non-challenged, NOC). Two bilateral patches at the measurement sites were treated simultaneously with a gel containing sodium nitrate and ascorbic acid, to generate nitric oxide (NO), and a vehicle gel. Blood flow was measured by laser Doppler velocimetry. Changes induced by these treatments were calculated against basic blood flow values for the corresponding patch. The results showed that the basic blood flow over the abdominal skin patches at room temperature was higher than over the dorsal skin in both acclimation states, but comparison revealed a sustainably higher level of basic skin blood flow in the WAC pigeons. The local response to exogenous NO was non-uniform over the two skin areas measured, and a specific vasodilatory action on the abdominal microvessels was recorded in the NOC pigeons. Abdominal vasodilatation in the WAC pigeons seemed to involve other mechanisms as well as local NO-dependent ones, among which the role of cold-induced vasodilatation (CIVD) is discussed here. Interestingly, the dorsal skin seemed to be less responsive to the action of NO, irrespective of the acclimation state. Our results show that acclimation state and skin site affect the action of exogenous NO on local skin blood flow, and we suggest that the differences reflect acclimation-induced changes in the vascularity of the skin and in its sensitivity to thermal stimuli and that the roles of the abdominal and dorsal skin are different with respect to environmental changes.

l-Menthol attenuates the magnitude of cold-induced vasodilation on the extremities of young females

“…Among these, the third and last are the most important explanatory factors for a locally driven mechanism. Meanwhile, with regard to the release of dilating substances, there is evidence of a link between CIVD and nitric oxide (NO) concentration in birds [ 18 ]. This is also supported by a human study on the involvement of NO in the cutaneous vasoconstrictor response to local cooling [ 19 ], though the results of these studies cannot be precisely applied into the explanation of CIVD.…”

Contribution of nucleus raphe magnus to thermoregulation

“…Capillary blood flow per se is considered to be principally regulated by local factors, of which NO appears to be the most powerful. Nitric oxide, due to its short half-life of only a few seconds, is believed to be a severely local regulating factor skin blood flow (Peltonen and Pyörnilä, 2004). NO plays a significant role in causing the dorsal column stimulation-induced enhancement in rat cutaneous hind paw blood flow (Croom et al, 1997).…”

Dynamic Adaptation of the Peripheral Circulation to Cold Exposure

“…Also, cooling reduces the contraction to adrenergic activation in cutaneous vessels of rabbit ears [31]. More recently, Peltonen and Pyornila [61] observed a link between CIVD and NO concentration in birds. However, to our knowledge, the involvement of NO during CIVD has not yet been established in humans.…”