Abstract
Ring preparations of the superficial buccal segment of the human facial vein, taken from extirpated tissue in 12 patients during neck surgery, were studied in vitro. The vein developed a maintained intrinsic myogenic tone in response to passive stretch and was supplied with alpha- as well as beta-adrenoceptors, both of which could be influenced by transmural nerve stimulation (TNS) and noradrenaline. These unusual characteristics for a vein are basically similar to the ones described for the rabbit facial vein by Pegram, Bevan & Bevan (1976). In man there seemed to be an inter-individual difference with regard to the abundance of 'innervated' alpha- and beta-adrenoceptors. Facial vein specimens from some subjects thus responded with prompt and pronounced net dilatation to TNS with maximum at 4 Hz and those from others with net constriction with maximum at 16 Hz. The latter showed a reversal into neural beta-adrenergic dilatation after alpha-adrenergic blockade. The human external jugular vein was devoid of intrinsic tone and beta-adrenoceptors. It is tentatively proposed that a beta-adrenergic neuro-effector mechanism in superficial ramifications of the facial vein in man might be involved in the emotional blushing reaction.
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