Circulatory Effects Caused by Intra-Arterial Infusion of AMP, ADP and ATP in the Canine Facial and Nasal Vascular Beds

Abstract

The effects of the intra-arterial infusion of ATP, ADP and AMP into the internal maxillary artery (IMA), which provides the blood supply to the nasal and forehead regions of the dog, were analyzed. Total blood flow and perfusion pressure measurements in the IMA after administration of each adenyl compound indicated dose-dependent and active vasodilatory responses that were restricted to the ipsilateral vessels. The rank order of potency was ADP ≧ ATP > AMP. In order to determine the microcirculatory effects caused by ADP, the tracer microsphere technique combined with absolute blood flow measurement was used. Intra-arterial infusion of ADP in the range 1-200 nmol/min produced elevations in the IMA flow on the stimulated side that ranged between 11 and 74%. The responses to low doses of ADP were mainly confined to the capillaries (CAP), whereas the arteriovenous anastomoses too were sensitive to high doses. The relative contributions of the anatomically and functionally different compartments of the forehead and nose to ADP-produced relaxations of the CAP were dependent upon their location. The CAP flows in the tissues which play a crucial role in conditioning the inspired air increased significantly, while the compartments of the furred surfaces were less sensitive to ADP. The results suggest that, since ATP, ADP and AMP are effective vasodilatory agents in all the regions examined, purines could have a regulatory or modulatory role in the complex vascular regulation of the nasal and forehead regions.

Purinergic Signaling and Blood Vessels in Health and Disease

“…Human isolated subcutaneous resistance arteries were shown to dilate via P2Y and P1 receptors and constrict via P2X receptors (Martin et al, 1991). Intra-arterial infusion of ATP, ADP, and AMP in canine facial and nasal vascular Purinergic Signaling and Blood Vessels beds caused vasodilation (Bari et al, 1993). Purinergic agonists [ATP and adenosine-59-(g-thio)-triphosphate (ATPgS)] induce release of inflammatory mediators from human dermal microvascular endothelial cells (Bender et al, 2008).…”

Effects of Calcium Channel Blockers on Cold-Induced Vasodilatation and Elevated Sympathetic Tone in the Canine Internal Maxillary Artery Bed

“…We did not observe such a reac tion when we studied the effects of other, more potent vasodilatory substances (e.g. histamine, VIP, ADP and bradykinin) in the internal maxillary artery vascular bed in previous experiments [10][11][12].…”

“…The detailed methods of the anesthesia and surgical procedure were described previously [11,12,21]. In brief, anesthesia was induced with a combination of ketamine hydrochloride (Ketavet, Parke Davis, Berlin, Germany, 12 nig/kg) and acepromazine maleate (Vetranquil.…”

“…The fine adjustment of the nasal blood flow is achieved by alteration of the flow and heat transport in the nasal and facial tissues dur ing cold exposure [3,4], Besides adrenergic and cholinergic efferents, the in volvement of non-adrenergic, non-cholinergic and pep tide-containing afferent sensory fibres in the adaptation of the blood How of the upper respiratory tract to the envi ronmental demands is also documented [5][6][7][8][9]. It can fur ther be assumed that circulating and/or locally released vasoactive substances play an important role in the pre cise control of the microcirculation in this region [10][11][12]. However, the mechanisms underlying the cold-induced vascular changes (i.e.…”

“…19]. The radioactive microsphere tracer technique (with cer tain known limitations) has proved a reliable method in studies of the microcirculation in the nasal and facial tis sues [3,11,12,20].…”