Changes in calcium signalling in dorsal horn neurons in rats with streptozotocin-induced diabetes.
Intracellular calcium signalling was studied in the dorsal horn from neurons of rats with streptozotocin-induced diabetes versus control animals. The cytoplasmic Ca2+ concentration ([Ca2+]i) was measured in Fura-2 acetoxymethyl ester-loaded dorsal horn neurons from acutely isolated spinal cord slices using a fluorescence technique. The recovery of depolarization-induced [Ca2+]i increase was delayed in diabetic neurons compared with normal animals. In normal neurons, [Ca2+]i after the end of KCl depolarization recovered to the basal level monoexponentially with a time constant of 8.0+/-0.5 s (n = 23), while diabetic neurons showed two exponentials in the [Ca2+]i recovery. The time constants of these exponentials were 7.2+/-0.5 and 23.0+/-0.6 s (n = 19), respectively. The amplitude of calcium release from caffeine-sensitive endoplasmic reticulum calcium stores became significantly smaller in diabetic neurons. The amplitudes of [Ca2+]i transients evoked by 30 mM caffeine were 268+/-29 nM (n = 13) and 31+/-9 nM (n = 17) in control and diabetic neurons, respectively. We conclude that streptozotocin-induced diabetes is associated with prominent changes in the mechanisms responsible for [Ca2+]i regulation, which presumably include a slowdown of Ca2+ elimination from the cytoplasm by the endoplasmic reticulum.
Voitenko
N V
NV
Department of General Physiology of the Nervous System, Bogomoletz Institute of Physiology, Kiev, Ukraine. nana@serv.biph.kiev.ua
Kostyuk
E P
EP
Kruglikov
I A
IA
Kostyuk
P G
PG
D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D003593:Cytoplasm / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000503:physiopathology*; D005456:Fluorescent Dyes; D016257:Fura-2 / Q000031:analogs & derivatives; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D020671:Posterior Horn Cells / Q000187:drug effects / Q000502:physiology*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D015398:Signal Transduction / Q000502:physiology*; D013116:Spinal Cord / Q000502:physiology / Q000503:physiopathology
D005456:Fluorescent Dyes; C049925:fura-2-am; D002110:Caffeine; D011189:Potassium Chloride; D002118:Calcium; D016257:Fura-2