Johnson C D, Coney A M, Marshall J M
Department of Physiology, Medical School, University of Birmingham, United Kingdom.
Am J Physiol Heart Circ Physiol. 2001 Dec;281(6):H2432-40. doi: 10.1152/ajpheart.2001.281.6.H2432.
In anesthetized rats, we characterized the contributions of norepinephrine (NE) and ATP to changes in tail and hindlimb (femoral) vascular resistances (TVR and FVR, respectively) evoked by three patterns of sympathetic stimulation: 1) couplets (2 impulses at 20 Hz), 2) short trains (20 impulses at 20 Hz), and 3) a natural irregular pattern previously recorded from a sympathetic fiber innervating the rat tail artery. All stimuli evoked greater changes in TVR than FVR. Judging from the effects of the alpha-adrenoceptor antagonist phentolamine, the purinergic receptor antagonist suramin, or alpha,beta-methylene ATP (which desensitizes P2X receptors), we propose that NE has a major role in the constriction evoked by the couplet, as well as by the short train and by the low- and high-frequency components of the natural pattern, but that considerable synergy occurred between the actions of ATP and NE. This contrasts with previous in vitro studies that indicated that ATP dominates vascular responses evoked by sympathetic stimulation with a few impulses at low frequency and that NE dominates responses to longer trains or at high frequencies.
在麻醉大鼠中，我们研究了去甲肾上腺素（NE）和三磷酸腺苷（ATP）对三种交感神经刺激模式引起的尾部和后肢（股部）血管阻力变化（分别为TVR和FVR）的作用：1）成对刺激（20 Hz的2个脉冲），2）短串刺激（20 Hz的20个脉冲），以及3）先前从支配大鼠尾动脉的交感神经纤维记录到的自然不规则模式。所有刺激引起的TVR变化均大于FVR。从α-肾上腺素能受体拮抗剂酚妥拉明、嘌呤能受体拮抗剂苏拉明或α,β-亚甲基ATP（使P2X受体脱敏）的作用判断，我们认为NE在成对刺激、短串刺激以及自然模式的低频和高频成分引起的血管收缩中起主要作用，但ATP和NE的作用之间存在相当大的协同作用。这与先前的体外研究形成对比，先前的研究表明，ATP在低频少量脉冲的交感神经刺激引起的血管反应中起主导作用，而NE在对较长串刺激或高频刺激的反应中起主导作用。
