Histamine lipolysis II: effects of histamine and related compounds on membrane potentials of rat adipocytes
Akiyama, Y.; Kamei, C.; Tasaka, K.
Methods and Findings in Experimental and Clinical Pharmacology 12(7): 457-465
1990
ISSN/ISBN: 0379-0355 PMID: 2087145 Document Number: 347689
The effects of histamine (Hi) and related compounds on rat mesenterial adipocytes were investigated using electrophysiological techniques. Hi caused a concentration-related depolarization and significant effect was observed at concentrations higher than 5 .times. 10-6 M. Effective membrane resistance was also decreased by Hi. The H1-agonists 2-methylHi and 2-thiazolylethylamine caused no depolarization even at a concentration of 5 .times. 10-4 M, but the H2-agonists, 4-methylHi and impromidine decreased resting membrane potentials. While 4-methylHi was less potent than Hi, impromidine was more potent. The H1-antagonists diphenhydramine and pyrilamine did not affect Hi-induced depolarization. However, H2-antagonists like cimetidine and ranitidine caused a significant inhibition even at a concentration of 10-6 M. As in the case of isoproterenol, the decrease in resting membrane potentials induced by Hi was significantly potentited by theophylline. Dibutyryl cyclic AMP treatment and intracellular application of cyclic AMP also caused a marked depolarization.