Poli E, Pozzoli C
Institute of Pharmacology, School of Medicine, University of Parma, Italy.
Eur J Pharmacol. 1997 May 26;327(1):49-56. doi: 10.1016/s0014-2999(97)89677-x.
We investigated the role played by histamine H3 receptors in the control of intestinal peristalsis, using two different in vitro preparations of guinea-pig ileum. (a) Ileal segments were perfused from the oral end, inducing peristaltic movements (emptying waves), due to the activation of intramural reflexes. Such peristaltic motility was measured as changes in the perfusion pressure during the emptying phase and the threshold pressure for triggering the emptying wave was determined. (b) Ileal segments were mounted horizontally and circular muscle contraction evoked by the ascending peristaltic reflex was triggered by caudal distension of the intestinal wall. In perfused ileal segments, specific agonists acting at histamine H3 receptors, ((R)-alpha-methylhistamine and immepip, 1 nmol-10 micromol/l), did not cause any change in the threshold pressure for triggering the peristaltic wave, or in the rise of the perfusion pressure during the emptying phase. Similarly, circular muscle contractions evoked by caudal distension of the wall were not affected by these histamine H3 receptor agonists up to 10 micromol/l. In the same conditions, a complete inhibition of peristaltic movements was elicited by agonists acting at alpha2-adrenoceptors or adenosine A1 receptors (compound UK 14,304 and N6-cyclopentyladenosine, respectively), their effects being prevented by the respective receptor antagonists, idazoxan and 8-cyclopentyl-1,3-dimethyl-xanthine. These data demonstrate that, contrary to alpha2-adrenoceptors and adenosine A1 receptors, histamine H3 receptors are not primarily involved in the modulation of intramural reflexes that modulate the peristaltic motility of the isolated guinea-pig ileum.
我们使用两种不同的豚鼠回肠体外制备方法，研究了组胺H3受体在肠道蠕动控制中所起的作用。(a) 回肠段从口腔端进行灌注，由于壁内反射的激活，引发蠕动运动（排空波）。这种蠕动运动通过排空阶段灌注压力的变化来测量，并确定触发排空波的阈值压力。(b) 回肠段水平安装，通过肠壁的尾端扩张引发由升结肠蠕动反射引起的环行肌收缩。在灌注的回肠段中，作用于组胺H3受体的特异性激动剂（(R)-α-甲基组胺和依美哌啶，1 nmol - 10 μmol/L），在触发蠕动波的阈值压力或排空阶段灌注压力的升高方面未引起任何变化。同样，高达10 μmol/L的这些组胺H3受体激动剂对由壁尾端扩张引起的环行肌收缩没有影响。在相同条件下，作用于α2肾上腺素能受体或腺苷A1受体的激动剂（分别为化合物UK 14,304和N6-环戊基腺苷）可完全抑制蠕动运动，它们的作用可被各自的受体拮抗剂咪唑克生和8-环戊基-1,3-二甲基黄嘌呤所阻断。这些数据表明，与α2肾上腺素能受体和腺苷A1受体相反，组胺H3受体并非主要参与调节孤立豚鼠回肠蠕动运动的壁内反射的调制。
