title: Regulation of NK cell activity and the level of the intracellular cAMP in human peripheral blood lymphocytes by Met-enkephalin.
abstract: The effect of Met-enkephalin on natural killer (NK) activity and on intracellular cyclic adenosine monophosphate (cAMP) level in human peripheral blood lymphocytes was measured 1/4, 1, 2, and 24 h after incubation. Concentrations of Met-enkephalin ranged from 10(-12) to 10(-8) M. Cyclic changes in NK activity and in the intracellular cAMP level after treatment with Met-enkephalin were observed. Kinetics of changes caused by high (10(-9), 10(-8) M) and low concentrations (10(-12), 10(-11), 10(-10) M) of Met-enkephalin differed from each other. Early, nearly threefold increase in the level of intracellular cAMP was found 15 min after treating peripheral blood lymphocytes with 10(-12) M Met-enkephalin. By contrast, a nearly 75% decrease of intracellular cAMP level was found 2 h after treatment with 10(-9) M Met-enkephalin. Generally, early intensive changes in the cAMP level in peripheral blood lymphocytes, induced by Met-enkephalin, were followed by delayed, subtle changes in NK cell activity in the opposite direction.
authors.affiliation: Department of Experimental Biology and Medicine, Ruder Bosković Institute, Zagreb, Croatia.
authors.forename: I
authors.initials: I
authors.lastname: Martin-Kleiner
authors.forename: M
authors.initials: M
authors.lastname: Osmak
authors.forename: J
authors.initials: J
authors.lastname: Gabrilovac
mesh_terms: D000293:Adolescent; D000328:Adult; D000242:Cyclic AMP / Q000032:analysis*; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007694:Killer Cells, Natural / Q000187:drug effects*; D008214:Lymphocytes / Q000737:chemistry / Q000187:drug effects*; D008297:Male
chemical_list: D004744:Enkephalin, Methionine; D000242:Cyclic AMP