Protection from high pressure induced hyperexcitability by the AMPA/kainate receptor antagonists GYKI 52466 and LY 293558. 1994

P C Pearce, and C J Maclean, and H K Shergill, and E M Ward, and M J Halsey, and G Tindley, and J Pearson, and B S Meldrum
Anaesthesia/HPNS group, MRC Clinical Research Centre, Harrow, Middlesex, U.K.

The neurophysiological effects of 2 novel AMPA/kainate receptor antagonists, GYKI 52466 and LY 293558, on the high pressure neurological syndrome have been investigated in the rat and baboon (GYKI 52466) and rat (LY 293558). Rats were exposed to increasing ambient pressures of helium and oxygen at 3 ATA/min, on one occasion each. GYKI 52466 at 20 mumol/kg i.v. immediately before, followed by 70 mumol/kg/hr i.v. during compression delayed tremor by 85% and myoclonus by 30%, compared with control vehicle, and no side effects were observed. Seizure activity was not affected by any of the doses used. LY 293558 at 36 mumol/kg i.p. delayed tremor and myoclonus (44% and 12%), LY 293558 72 mumol/kg additionally delayed seizure activity (21%). Side effects, principally tranquilization at the higher dose, were also noted. Six baboons were exposed to a maximum pressure of 91 ATA at 0.3 ATA/min, in the same environment, on two occasions. One exposure was treated with an i.v. infusion of GYKI 52466 15.2 mumol/kg/hr, the other with the same volume of control vehicle. Limb and face tremor and myoclonus were delayed and the severity of signs reduced. No seizures were observed in the drug treated group before 91 ATA. EEG changes associated with exposure to pressure were not affected. It is concluded that antagonism at the AMPA/kainate receptor by GYKI 52466 and LY 293558 beneficially alters HPNS signs but in a manner which is dependent on both the drug and species being studied.

UI MeSH Term Description Entries
D007262 Infusions, Intravenous The long-term (minutes to hours) administration of a fluid into the vein through venipuncture, either by letting the fluid flow by gravity or by pumping it. Drip Infusions,Intravenous Drip,Intravenous Infusions,Drip Infusion,Drip, Intravenous,Infusion, Drip,Infusion, Intravenous,Infusions, Drip,Intravenous Infusion
D007274 Injections, Intraperitoneal Forceful administration into the peritoneal cavity of liquid medication, nutrient, or other fluid through a hollow needle piercing the abdominal wall. Intraperitoneal Injections,Injection, Intraperitoneal,Intraperitoneal Injection
D007275 Injections, Intravenous Injections made into a vein for therapeutic or experimental purposes. Intravenous Injections,Injection, Intravenous,Intravenous Injection
D007546 Isoquinolines A group of compounds with the heterocyclic ring structure of benzo(c)pyridine. The ring structure is characteristic of the group of opium alkaloids such as papaverine. (From Stedman, 25th ed)
D008297 Male Males
D009207 Myoclonus Involuntary shock-like contractions, irregular in rhythm and amplitude, followed by relaxation, of a muscle or a group of muscles. This condition may be a feature of some CENTRAL NERVOUS SYSTEM DISEASES; (e.g., EPILEPSY, MYOCLONIC). Nocturnal myoclonus is the principal feature of the NOCTURNAL MYOCLONUS SYNDROME. (From Adams et al., Principles of Neurology, 6th ed, pp102-3). Myoclonus, Action,Myoclonus, Nocturnal,Myoclonus, Palatal,Polymyoclonus,Myoclonic Jerk,Myoclonic Jerking,Myoclonus Simplex,Myoclonus, Eyelid,Myoclonus, Intention,Myoclonus, Lower Extremity,Myoclonus, Oculopalatal,Myoclonus, Segmental,Myoclonus, Sleep,Myoclonus, Upper Extremity,Action Myoclonus,Extremity Myoclonus, Lower,Extremity Myoclonus, Upper,Eyelid Myoclonus,Intention Myoclonus,Jerk, Myoclonic,Jerking, Myoclonic,Jerks, Myoclonic,Lower Extremity Myoclonus,Myoclonic Jerks,Nocturnal Myoclonus,Oculopalatal Myoclonus,Palatal Myoclonus,Segmental Myoclonus,Simplex, Myoclonus,Sleep Myoclonus,Upper Extremity Myoclonus
D010215 Papio A genus of the subfamily CERCOPITHECINAE, family CERCOPITHECIDAE, consisting of five named species: PAPIO URSINUS (chacma baboon), PAPIO CYNOCEPHALUS (yellow baboon), PAPIO PAPIO (western baboon), PAPIO ANUBIS (or olive baboon), and PAPIO HAMADRYAS (hamadryas baboon). Members of the Papio genus inhabit open woodland, savannahs, grassland, and rocky hill country. Some authors consider MANDRILLUS a subgenus of Papio. Baboons,Baboons, Savanna,Savanna Baboons,Baboon,Baboon, Savanna,Papios,Savanna Baboon
D004569 Electroencephalography Recording of electric currents developed in the brain by means of electrodes applied to the scalp, to the surface of the brain, or placed within the substance of the brain. EEG,Electroencephalogram,Electroencephalograms
D005260 Female Females
D006610 High Pressure Neurological Syndrome A syndrome related to increased atmospheric pressure and characterized by tremors, nausea, dizziness, decreased motor and mental performance, and SEIZURES. This condition may occur in those who dive deeply (c. 1000 ft) usually while breathing a mixture of oxygen and helium. The condition is associated with a neuroexcitatory effect of helium. Experimental High Pressure Neurological Syndrome,HPNS,High Pressure Nervous Syndrome,High Pressure Neural Syndrome,High Pressure Neurological Syndrome, Experimental,HPNSs

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