Intravenous histamine causes high amplitude repetitive phasic contractions of the in vivo cat pylorus but has little effect on the antrum and duodenum. The genesis of this phasic response was studied using a pinned perfused catheter with openings at the pylorus, antrum, and duodenum. 2-Pyridylethylamine, an H1 agonist, produced phasic contractions similar to histamine whereas dimaprit, an H2 ag...

Histamine Hi and H2 receptors are present in the canine renal circulation. We have examined the effects of H, and H2 receptor antagonists on autoregulation of renal blood flow in the dog. Renal arterial pressure was reduced in a step-wise fashion to 80 mm Hg by means of an adjustable aortic clamp positioned above the left renal artery. Infusion of H2 antagonists, cimetidine or ranitidine, into ...

Activation of alpha 1-adrenergic receptors in BC3H-1 muscle cells has been shown previously to mobilize intracellular Ca2+, which can be monitored as enhanced 45Ca2+ unidirectional efflux. We report here that histamine also stimulates 45Ca2+ efflux in these cells (Kact = 5.50 microM, nH = 0.94 +/- 0.04), reflecting mobilization of intracellular Ca2+ from a source similar to that accessed by alp...

Non-reinforced retrieval induces memory extinction, a phenomenon characterized by a decrease in the intensity of the learned response. This attribute has been used to develop extinction-based therapies to treat anxiety and post-traumatic stress disorders. Histamine modulates memory and anxiety but its role on fear extinction has not yet been evaluated. Therefore, using male Wistar rats, we dete...

Vasoactive intestinal peptide (VIP) is known to induce histamine release in human skin and known to include a NO-dependent dilation in several other vascular beds. However, the relative contribution of histamine and NO to VIP-mediated vasodilation in human skin is unknown. Forty three subjects volunteered to participate in two studies designed to examine the mechanism of VIP-mediated vasodilati...

Vasoactive intestinal peptide (VIP) is known to induce histamine release in human skin and to include a nitric oxide (NO)-dependent dilation in several other vascular beds. However, the relative contribution of histamine and NO to VIP-mediated vasodilation in human skin is unknown. Forty-three subjects volunteered to participate in two studies designed to examine the mechanism of VIP-mediated v...

2-pyridyl]oxy-(Z)-2-butenyl] acetamide, is a newly developed histamine H2-receptor antagonist. It is at present only approved in Japan as a tablet, and is used in the treatment of gastric ulcers, duodenal ulcers, and gastric mucosal lesions associated with acute gastritis and acute exacerbation of chronic gastritis. Lafutidine possesses a potent and longlasting gastric antisecretory effect medi...

The possible role of histamine receptors in the hippocampal formation on the exploratory motivation and emotionality of the rat was studied. An elevated asymmetric plus-maze composed of 4 different arms (no walls, single high wall, high and low walls and two high walls) arranged at 90 degrees angles was used. The exploration score, considered to be an index of exploratory motivation, and the pe...

BACKGROUND A human neuroblastoma cell line (Paju) was induced by retinoic acid (RA) to differentiate into neuron-like cells. MATERIALS AND METHODS We studied the expression and the possible role of histamine receptors H1 and H2 in retinoic-acid mediated differentiation by semiquantitative RT-PCR. We studied the effect of exogeneously added RA on the morphological change of the human neuroblas...