Chronic hyperglycaemia increases neuronal sensitivity to high potassium in hippocampal slices from streptozotocin-treated diabetic rats.
The chronic hyperglycaemia associated with diabetes mellitus increases susceptibility to epileptiform-like activity in the central nervous system. Changes in extracellular potassium levels directly influence neuronal excitability and significantly one of the major regulators of extracellular potassium, the Na-K ATPase, is known to be down-regulated by chronic hyperglycaemia. The sensitivity of hippocampal slices, from rats made diabetic for 2-3 weeks with streptozotocin, to increases in the extracellular potassium concentration ([K+]o) was, therefore, investigated. Raising [K+]o to 10 mM increased the number of orthodromically-evoked population spikes (PSs) in area CA1. This recruitment was significantly greater in hippocampal slices from diabetic rats, which also exhibited significantly more spontaneous activity. These findings confirm a diabetes-dependent increase in sensitivity of central neurones to changes in [K+]o and may help to explain the increased susceptibility to epileptiform activity in this disease state.
Candy
S M
SM
Cellular and Integrative Biology, Division of Biomedical Sciences, Imperial College School of Medicine, London, UK.
Szatkowski
M S
MS
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000503:physiopathology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology / Q000503:physiopathology*; D006943:Hyperglycemia; D066298:In Vitro Techniques; D008297:Male; D011188:Potassium / Q000494:pharmacology*; D017966:Pyramidal Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
D001786:Blood Glucose; D011188:Potassium