CHRONIC LEAD TREATMENT ACCELERATES PHOTOCHEMICALLY INDUCED PLATELET-AGGREGATION IN CEREBRAL MICROVESSELS OF MICE, IN-VIVO

Effects of two chronic treatment levels with lead on platelet aggregat ion in cerebral (pial) microcirculation of the mouse were investigated . Exposure to lead was made by subcutaneous injections for 7 days of l ead acetate dissolved in 5% glucose solution, vehicle. Two doses of le ad were used, a low dose of 0.1 mg/kg and a high dose of 1.0 mg/kg. Ad ult male mice were divided into three groups, 10 each; one group was i njected with vehicle (control), another was injected with the low dose , and the third was injected with the high dose. Additional mice were used for the determination of hematological parameters and for the lea d level in serum of the three groups. On the eighth day, platelet aggr egation in pial microvessels of these groups of mice was carried out i n vivo. Animals were anesthetized (urethane, 1-2 mg/g, ip), the trache a was intubated, and a craniotomy was performed. Platelet aggregation in pial microvessels was induced photochemically, by activation of cir culating sodium fluorescein (0.1 mg/25 g, iv) with an intense mercury light. The time required for the first platelet aggregate to appear in pial arterioles was significantly shorter in the lead-treated mice th an in control. This effect was in a dose-dependent manner; 113 +/- 44 sec for low dose and 71 +/- 18 sec for high dose vs 155 +/- 25 sec for control, P < 0.02 and P < 0.001, respectively. Between the two lead-t reated groups, the high dose significantly (P < 0.05) shortened the ti me to first aggregate. These data evidenced an increased susceptibilit y to cerebrovascular thrombosis as a result of exposure to lead. (C) 1 995 Academic Press, Inc.