Serotonin and histamine H1, H2 receptor agonists or antagonists inhibited [3H]histamine uptake by HL-60 cells, according to the following order of potency: impromidine greater than 4-MH greater than histamine greater than AET greater than PEA and: cimetidine, histamine greater than diphenhydramine, serotonin. It is concluded that histamine uptake by HL-60 cells was specifically controlled by th...

The role of histamine in regulating excitability of sympathetic preganglionic neurons (SPNs) and the expression of histamine receptor mRNA in SPNs was investigated using whole-cell patch-clamp electrophysiological recording techniques combined with single-cell reverse transcriptase polymerase chain reaction (RT-PCR) in transverse neonatal rat spinal cord slices. Bath application of histamine (1...

The determinants for recognition at H3 histamine receptors are considered. Findings based on quantum-chemical calculations suggest that H3 histamine receptor is less hydrophilic than the H2. The form most likely to be recognized by the H3 receptor is an intramolecularly hydrogen-bonded form of alpha-methylhistamine. Receptor environment and hydration effects of active form of histamine analogs ...

The substantia nigra pars reticulata (SNr) is a key basal ganglia output nucleus. Inhibitory outputs from SNr are encoded in spike frequency and pattern of the inhibitory SNr projection neurons. SNr output intensity and pattern are often abnormal in movement disorders of basal ganglia origin. In Parkinson's disease, histamine innervation and histamine H3 receptor expression in SNr may be increa...

Whole cell perforated patch-clamp methods were used to investigate ionic mechanisms underlying histamine-evoked excitatory responses in small intestinal AH-type myenteric neurons. When physiological concentrations of Na(+), Ca(2+), and Cl(-) were in the bathing medium, application of histamine significantly increased total conductance as determined by stepping to 50 mV from a holding potential ...

Phospholipase Cbeta (PLCbeta) isozymes represent a family of molecules that link G protein-coupled receptors (GPCRs) to an intracellular signaling network. Here, we investigated the function of PLCbeta isozymes in sensory neurons by using mutant mice deficient for specific PLCbeta family members. Expression analysis indicated that PLCbeta3, one of the four isoforms, is predominantly expressed i...

Blood-tumor barrier (BTB) reduce the permeability for drugs into tumor tissues. We found that histamine might serve as an essential regulator of BTB function. Further, we aim to determine the role of H2 receptor expression in BTB permeability, and elucidate the underlying mechanisms thereof. Transmission electron microscopy showed that histamine disrupted the integrity of tight junctions (TJ) a...

Ascorbate has previously been shown to enhance both alpha(1)- and beta(2)-adrenergic activity. This activity is mediated by ascorbate binding to the extracellular domain of the adrenergic receptor, which also decreases the oxidation rate of ascorbate. H1 histamine receptors have extracellular agonist or ascorbate binding sites with strong similarities to alpha(1-) and beta(2)-adrenergic recepto...

INTRODUCTION The neuroendocrine histamine-secreting cell of the gastric fundus, the enferochromaffin-like cell, is the principal regulator of parietal cell acid secretion. We have proposed that histamine may regulate its own synthesis and release via an autocrine mechanism. The purpose of this study was to evaluate the role of the histamine receptor subtypes H1, H2 and H3 in the regulation of t...

We utilized the technique of polymerase chain reaction with oligonucleotide primers based upon the nucleotide sequence of the canine H2 histamine receptor gene which we recently isolated to clone its human homologue. Transfection of a construct of this gene in Colo-320 DM cells led to the expression of a receptor that bound to [methyl-3H] tiotidine and was linked to 3',5'cyclic adenosine monoph...