Increase of voltage-sensitive calcium channels and calcium accumulation in skeletal muscles of streptozocin-induced diabetic rats.
The number of voltage-sensitive calcium channels (VOCC) in triceps surae muscle membrane fractions isolated from control and streptozocin (STZ)-induced diabetic rats was determined using [3H]PN200-110, a dihydropyridine derivative, as a ligand. Furthermore, quantitative analysis of calcium in soleus muscle fibers was performed by the calcium oxalate-pyroantimonate method and x-ray microanalysis. The maximum binding (Bmax) of [3H]PN200-110 in skeletal muscle membrane isolated from 10-week diabetic rats (1,091 +/- 77 fmol/mg protein) was increased significantly by 91% as compared with the control value (572 +/- 32 fmol/mg protein), without a significant change in Kd. The increase in Bmax of [3H]PN200-110 was dependent on the duration of diabetes, and was not found until 6 weeks after STZ injection. Insulin treatment for 8 weeks after induction of diabetes normalized Bmax to the control level (583 +/- 53 fmol/mg protein). Precipitates of calcium antimonate, identified by x-ray microanalysis, were observed much more frequently in specimens from 10-week diabetic rats versus controls. The increase in the incidence of precipitates was not observed in 3-week diabetic rats and was suppressed by 8 weeks' insulin treatment. These results indicate that the number of VOCC in chronically diabetic rats was increased in the sarcolemmal membrane of skeletal muscle and that calcium was accumulated inside skeletal muscle fibers.
D000704:Analysis of Variance; D000818:Animals; D000965:Antimony / Q000032:analysis; D001786:Blood Glucose / Q000032:analysis; D002118:Calcium / Q000032:analysis / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D017610:Calcium Compounds / Q000032:analysis; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000378:metabolism* / Q000503:physiopathology; D004577:Electron Probe Microanalysis; D007328:Insulin / Q000097:blood; D008297:Male; D008872:Microwaves; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D013311:Streptozocin; D016707:Tissue Fixation; D014316:Tritium
D001786:Blood Glucose; D015220:Calcium Channels; D017610:Calcium Compounds; D007328:Insulin; D014316:Tritium; C006872:calcium antimonate; D013311:Streptozocin; D000965:Antimony; D002118:Calcium