Amelioration by the Ca2+ antagonist, nimodipine of an existing neuropathy in the streptozotocin-induced, diabetic rat.

1. Neuropathy is a frequently diagnosed complication in diabetic patients but an effective treatment does not exist. 2. The development of neuropathy in streptozotocin-induced diabetic rats was monitored by measuring the motor and sensory nerve conduction velocity in the sciatic nerve. 3. A significant decrease in sensory and motor nerve conduction velocity was apparent in young, 14-week-old diabetic rats as compared to non-diabetic, age-matched controls 4 weeks after the induction of diabetes with streptozotocin. 4. Intraperitoneal treatment with the Ca2+ channel blocker, nimodipine, from week 4 onwards, in a dosage of 10 mg kg-1 or 20 mg kg-1 intraperitoneally per 48 h, resulted in a significant increase in sensory and motor nerve conduction velocity whereas treatment with 5 mg kg-1 intraperitoneally per 48 h was not effective. 5. One-year-old, adult, diabetic rats treated with nimodipine 20 mg kg-1 (treatment started again 4 weeks after induction of diabetes mellitus) also showed an increase of both sensory and motor nerve conduction velocity as compared to diabetic rats treated with placebo. 6. It is concluded that nimodipine ameliorates existing experimental diabetic neuropathy in streptozotocin-induced diabetic rats in both young and adult animals.