Neural beta‐adrenergic dilatation of the facial vein in man Possible mechanism in emotional blushing

Negita

1987

Jpn.J.Pharmacol

Abstract-The buccal segment of the canine facial vein which was precontracted moderately with prostaglandin F2a relaxed to different extents in response to dopamine (DA), norepinephrine (NE), epinephrine (Epi) and isoproterenol (Isp). Propranolol (10-6 M) reversed the relaxation responses to contractions. In the presence of an a-adrenoceptor blockade and inhibitors of neuronal and extraneuronal uptakes, the four catecholamines relaxed the vein fully, and the order of pD2 values was Isp (8.34) > Epi (7.53) = NE (7.50) » DA (5.31). The results indicate that in the canine facial vein, 9-adrenoceptors predominate over a-adrenoceptors, and the subtype of (9-adrenoceptor may be the 41-type.

supporting

confidence: 49%

Effects of catecholamines on isolated canine facial veins.

Negita

1987

Jpn.J.Pharmacol

“…Overall, the results indicate that 81 and (32-subtypes coexist and that the (31-subtype predominates over the (32-subtype in the canine facial vein. This may profoundly contribute to the neural (3-adrenergic dilata tion in some proposed physiological roles of the facial vein, such as local cranial (brain) thermoregulation in rabbits (30) and emotional blushing in humans (31).…”

Section: Discussionmentioning

confidence: 99%

Heterogeneity of .BETA.-adrenoceptor in canine veins: Comparison among the facial, portal and saphenous veins.

Negita

1989

Jpn.J.Pharmacol

Abstract-A study was made on the characteristics of 13-adrenoceptors in the isolated canine facial, portal and saphenous veins. Ring segments of the facial and saphenous veins and longitudinal strips of the portal vein were suspended in tissue baths containing Krebs solution oxygenated and maintained at 37'C. They were moderately contracted with prostaglandin F2a before examining their relaxation responses.The facial and saphenous veins fully relaxed to isoproterenol, while the aortal vein relaxed to a small extent (20% of maximum relaxation) even in the presence of an a-adrenoceptor blockade.In contrast, both forskolin, a direct activator of adenylate cyclase, and membrane-permeable dibutyryl cyclic AMP similarly relaxed all the veins studied.

“…On the other hand, the facial vein of humans and some animals relaxes in response to sympathetic nerve stimulation (19,20). This peculiar response indicates that >- adrenoceptors predominate over =1-adrenoceptors in the facial vein.…”

Section: Diversity Of Adrenoceptor Types and Subtypesmentioning

confidence: 99%

“…This peculiar response indicates that >- adrenoceptors predominate over =1-adrenoceptors in the facial vein. In this way, physiological roles such as blushing in the human (20) and cranial thermoregulation in the rabbit (21) can be explained. Interestingly, >-adrenoceptor-mediated relaxation of the facial vein is mainly mediated by >1-adrenoceptors, as in the heart, and not by > 2-adrenoceptors, as in most smooth muscles, including blood vessels (22).…”

Section: Diversity Of Adrenoceptor Types and Subtypesmentioning

confidence: 99%

Pharmacology and Physiology of Perivascular Nerves Regulating Vascular Function

Japanese Journal of Pharmacology

Tanimitsu

Hirai

2002

ABSTRACT-Maintenance of blood pressure is mostly dependent on sympathetic "tone", and the sympathetic nerve innervates the entire vascular bed, excepting the capillaries. Although norepinephrine (NE) is the principal neurotransmitter released upon sympathetic nerve stimulation, neuropeptide Y and ATP are cotransmitters in various vascular tissues. In addition, dopamine and epinephrine, as well as acetylcholine, have been shown to be sympathetic neurotransmitters in specific vasculatures. Transmitter NE release is modified by a number of endogenous substances including the transmitter itself. Chronic denervation of the preganglionic fiber induces an increase in NE release per pulse, indicating postganglionic neuronal supersensitivity. So far, three main adrenoceptor types have been shown, =1, =2 and > , each of which is further divided into at least three subtypes, as well as the = 1L-adrenoceptor, a phenotype of the cloned = 1a-adrenoceptor, in the blood vessel. Thus, the response of vessels with different receptor types to a transmitter varies quantitatively and even qualitatively from one vessel to another. The remarkable diversity in the sympathetic innervation mechanism in the vascular system may play an important role in regional variations in the regulation of blood flow. The sympathetic nerve also exerts long-term trophic action on the blood vessel. In conclusion, the sympathetic nervous system plays an important role not only in the regulation of cardiovascular dynamics but in the maintenance of the vessel structure, as well.