Blocking effect of intraperitoneal injection of phenylalanine on high-threshold calcium currents in rat hippocampal neurones.
Calcium currents were recorded in cultured (5-7 days) hippocampal neurones isolated from one-day-old rats. The animals obtained intraperitoneal injections of L-phenylalanine which induces in the brain biochemical changes characteristic of phenylketonuria. It has been found that the amplitude of the low-threshold calcium current in L-phenylalanine-affected neurones was not appreciably changed compared with that in neurones from control (non-injected) animals. However, the amplitude of the high-threshold calcium current was essentially decreased. Its relative amplitude at Vt = +20 mV became 40 +/- 30% as contrasted to 416 +/- 130% in neurones from control animals (the amplitude of the calcium currents at Vt = -10 mV taken as 100%). The decrease remained during the whole time of culturing. Addition of L-tyrosine to the cultivation medium (50 microM) restored the high-voltage calcium current, its relative amplitude reaching 280 +/- 57%. The data are discussed in conjunction with the previously obtained results about antagonistic modulatory action of tyrosine and phenylalanine on the functioning of high-threshold calcium channels and possible mechanisms of brain dysfunction during phenylketonuria.
Martynyuk
A E
AE
Bogomoletz Institute of Physiology, Ukrainian Academy of Sciences, Kiev, U.S.S.R.
Savina
S
S
Skibo
G G
GG
D000818:Animals; D000831:Animals, Newborn; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D007274:Injections, Intraperitoneal; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010649:Phenylalanine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D012016:Reference Values
D015220:Calcium Channels; D010649:Phenylalanine