Voltage-dependent calcium currents are enhanced in dorsal root ganglion neurones from the Bio Bred/Worchester diabetic rat

J Physiol. 1995 Jul 15;486 ( Pt 2)(Pt 2):313-22. doi: 10.1113/jphysiol.1995.sp020814.

Abstract

1. Whole-cell, high-threshold, voltage-dependent calcium currents (ICa) were enhanced in acutely dissociated, capsaicin-sensitive dorsal root ganglion neurones from diabetic Bio Bred/Worchester (BB/W) rats, compared with those from age-matched, non-diabetic controls. The magnitude of the enhancement increased with the duration of diabetes, and reached significance at diabetic durations of 6 months (diabetic: 6.3 +/- 0.4 nA; current density (CD), 157 +/- 12 pA pF-1; means +/- S.E.M., n = 9, P < 0.01; control: 3.9 +/- 0.6 nA; CD, 116 +/- 11 pA pF-1; n = 18) and 8 months (diabetic: 7.6 +/- 0.4 nA; CD, 177 +/- 25 pA pF-1; n = 11, P < 0.005; control: 5.1 +/- 0.5 nA; CD, 111 +/- 26 pA pF-1; n = 15). Low-threshold, voltage-dependent ICa were also enhanced in neurones from animals diabetic for 8 months (diabetic: 2.5 +/- 0.7 nA, n = 4, P < 0.05; control: 0.7 +/- 0.5 nA, n = 6). 2. The ICa enhancement was prevented by long-term treatment of diabetic animals with an aldose reductase inhibitor (ARI; peak ICa at 6 months: 4.41 +/- 0.48 nA, n = 2; at 8 months: 4.32 +/- 0.60 nA, n = 9). 3. The ICa enhancement was not due to a shift in the voltage dependence of either the current-voltage relationship or steady-state inactivation. 4. The L channel antagonist nifedipine and preferential N channel antagonist omega-conotoxin GVIA (omega-CgTX) caused a greater inhibition of high-threshold ICa in diabetic neurones compared with controls (nifedipine: control: 25 +/- 3%, n = 26; diabetic: 36 +/- 7%, n = 11; omega-CgTX: control: 40 +/- 4%, n = 21; diabetic: 50 +/- 7%, n = 7). Diabetic neurones also demonstrated a significantly greater residual current (2.44 +/- 0.34 nA, n = 7) in the presence of both antagonists vs. controls (1.28 +/- 0.30 nA, n = 8, P < 0.05), suggesting that N-, L- and additional non-N-, non-L-type high-threshold ICa were enhanced.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Aldehyde Reductase / antagonists & inhibitors
  • Animals
  • Blood Glucose / analysis
  • Body Weight
  • Calcium Channels / physiology*
  • Diabetes Mellitus, Type 1 / pathology
  • Diabetes Mellitus, Type 1 / physiopathology*
  • Differential Threshold
  • Electrophysiology
  • Ganglia, Spinal / pathology
  • Ganglia, Spinal / physiopathology*
  • Homeostasis
  • Male
  • Neural Conduction
  • Neurons, Afferent / physiology*
  • Rats
  • Rats, Inbred BB
  • Reference Values

Substances

  • Blood Glucose
  • Calcium Channels
  • Aldehyde Reductase