Age-dependent supersensitivity to the glycogenolytic effect of K+ in the cerebral cortex of the spontaneously epileptic quaking mouse mutant.
K+, at concentrations reached in the extracellular space during neuronal activity (5-10 mM), promotes a time- and concentration-dependent hydrolysis of [3H]glycogen newly synthesized by mouse cerebral cortical slices. In the present study, the glycogenolytic action of K+ was examined in the neocortex of the quaking mouse, a spontaneously epileptic mutant characterized by deficient myelination of the CNS. The potency and efficacy of K+ in eliciting glycogen hydrolysis was greatly enhanced in cerebral cortical slices prepared from homozygous quaking mice (qk/qk) older than 7 weeks of age, indicating a supersensitive response to a metabolic action of the ion. A detailed ontogenic analysis showed an evolution of the supersensitive response to K+ which is reminiscent of the previously described increase in the number of alpha 2-adrenoreceptors in the brainstem of this mutant. In contrast to the altered response to K+, the glycogenolytic action of noradrenaline and vasoactive intestinal peptide reported earlier was equally expressed in qk/qk and in their unaffected littermates.
Hof
P R
PR
Département de Pharmacologie, Centre Médical Universitaire, Geneva, Switzerland.
Celio
M R
MR
Magistretti
P J
PJ
D000375:Aging / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D004827:Epilepsy / Q000378:metabolism / Q000503:physiopathology*; D006003:Glycogen / Q000378:metabolism*; D066298:In Vitro Techniques; D051379:Mice; D008810:Mice, Inbred C57BL; D008818:Mice, Neurologic Mutants / Q000378:metabolism / Q000502:physiology*; D011188:Potassium / Q000494:pharmacology*
D006003:Glycogen; D011188:Potassium