Author/Editor		Osredkar, D; Burnik-Papler, T; Pečavar, B; Kralj-Iglič, V; Kržan, M
Title		Kinetic and pharmacological properties of [(3)H]-histamine transport into cultured type 1 astrocytes from neonatal rats
Type		članek
Source		Inflamm Res
Vol. and No.		Letnik 58, št. 2
Publication year		2009
Volume		str. 94-102
Language		eng
Abstract		Objective and design: Astrocytes actively participate in the inactivation of neurotransmitters. In this work we elucidated the contribution of astrocytes in clearance of histamine, a process which has not yet been fully clarified.Methods: The characteristics of [(3)H]-histamine uptake were determined in cultured neonatal rat type 1 astrocytes and histamine-N-methyl-transferase expression was determined using RT-PCR.Results: These cells transport [(3)H]-histamine in a time- and concentration-dependent manner. The histamine clearance by astrocytes was described by a mathematical model including two processes: electrodiffusion and active transport. A further analysis of kinetic parameters of a carrier-operated transport revealed a single transport system with Michaelis constant (K(m)) of 3.5 +/- 0.8 muM and a maximal uptake rate (V(max)) of 7.9 +/- 0.3 pmol/mg protein/min. From drugs tested amitriptyline, desipramine, mepyramine and cimetidine significantly decreased [(3)H]-histamine uptake. Taken-up histamine could be metabolically degraded in cultured astrocytes, since they express mRNA for enzyme histamine-N-methyltransferase.Conclusion: Astrocytes participate in the clearance of extracellular histamine by electrodiffusion and active transport by a yet not identified carrier. Taken up histamine can be converted to tele-methylhistamine within astrocytes thus indicating the involvement of astrocytes not only in clearance but also in the inactivation of histamine.
Descriptors		ASTROCYTES HISTAMINE HISTAMINE METHYLTRANSFERASE BIOLOGICAL TRANSPORT, ACTIVE POLYMERASE CHAIN REACTION KINETICS CELLS, CULTURED ANIMALS, NEWBORN RATS, WISTAR