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Sympathetic vascular control of the pig nasal mucosa: adrenoceptor mechanisms in blood flow and volume control
Author(s) -
Lacroix JeanSilvain,
Lundberg Jan M.
Publication year - 1989
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1989.tb12564.x
Subject(s) - oxymetazoline , phenylephrine , prazosin , agonist , vasoconstriction , vasodilation , rauwolscine , endocrinology , idazoxan , medicine , chemistry , antagonist , blood pressure , receptor
1 The adrenoceptor mechanisms influencing the total blood flow, volume and superficial blood flow in the nasal mucosa of pigs anaesthetized with pentobarbitone have been characterized by use of various agonists and antagonists. 2 Local intra‐arterial bolus injection of the selective α 1 ‐agonist phenylephrine, the selective α 2 ‐agonist UK 14.304, the mixed α 1 /α 2 ‐agonist oxymetazoline and the mixed α/β‐agonists noradrenaline (NA) and adrenaline induced dosed‐related reduction of nasal arterial blood flow (BF), nasal mucosal volume (V, reflecting capacitance vessel function) and the laser Doppler flowmetry signal (LDF, reflecting superficial movement of blood cells). The rank order of α‐agonist potency regarding BF reduction was UK 14.304 > oxymetazoline > NA > phenylephrine = adrenaline. For the volume response the potency order was UK 14.304 > oxymetazoline = NA = adrenaline > phenylephrine while for the reduction of the LDF signal the potency was UK 14.304 = NA = adrenaline > oxymetazoline > phenylephrine. The selective β 2 ‐agonist terbutaline caused dose‐dependent increase of BF whereas only a small augmentation of the V was obtained upon the highest dose (40 nmol) while no modification of the LDF signal was observed. 3 After pretreatment with the selective α 1 ‐antagonist prazosin, the response to phenylephrine was abolished while the selective α 2 ‐antagonist idazoxan attenuated the effect of UK 14.304. After pretreatment with α‐antagonists, both NA and adrenaline caused biphasic effects with constriction followed by vasodilatation for BF, but not for V or LDF. This vasodilatation was blocked by the β‐antagonist propranolol. 4 The reduction in nasal BF and V upon sympathetic nerve stimulation was attenuated both by prazosin and idazoxan. Propranolol enhanced the remaining reduction of BF but not of V in the presence of α‐antagonists. 5 It is concluded that α 2 ‐adrenoceptor mechanisms in the pig nasal mucosa are dominating for the BF, V and LDF responses to exogenous agonists, α 1 ‐Adrenoceptors also seem to be involved in the sympathetic control of BF, V and LDF. Activation of β 2 ‐receptors increases mainly BF and does not influence the LDF signal.