title: Evidence for the existence of histamine H1- and H2-receptors on astrocytes of cultured rat central nervous system.
abstract: By means of intracellular microelectrodes we have studied the action of histamine H1- and H2-agonists and -antagonists on the membrane potential of astrocytes in cultured rat brainstem and spinal cord. Histamine at high concentrations (10(-4) and 10(-5) M) mainly depolarized the glial membrane, whereas at low concentration (10(-6) M) it usually caused hyperpolarizations. The histamine-induced depolarizations were reversibly blocked by the H1-antagonist pyrilamine, whereas the H2-antagonist cimetidine antagonized the hyperpolarizations. The H1-agonist thiazolethylamine mainly produced depolarizations while impromidine, a H2-agonist, predominantly caused hyperpolarizations. Our findings, together with autoradiographic binding studies, provide strong evidence for the existence of histamine H1- and H2-receptors on astrocytes.
mesh_terms: D000631:Aminopyridines / Q000494:pharmacology*; D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology*; D001933:Brain Stem / Q000502:physiology*; D002478:Cells, Cultured; D002927:Cimetidine / Q000494:pharmacology*; D006632:Histamine / Q000494:pharmacology*; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D011738:Pyrilamine / Q000494:pharmacology*; D051381:Rats; D011968:Receptors, Histamine / Q000502:physiology*; D011969:Receptors, Histamine H1 / Q000502:physiology*; D011970:Receptors, Histamine H2 / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology*; D013844:Thiazoles / Q000494:pharmacology*
chemical_list: D000631:Aminopyridines; D006634:Histamine H1 Antagonists; D011968:Receptors, Histamine; D011969:Receptors, Histamine H1; D011970:Receptors, Histamine H2; D013844:Thiazoles; C029345:2-(2-aminoethyl)thiazole; D002927:Cimetidine; D006632:Histamine; D011738:Pyrilamine