Lymphocyte β₂-adrenergic receptors and plasma catecholamine levels in lead-exposed workers

The effect of lead exposure on β₂-adrenoceptor density and catecholamine response was studied in 26 male workers and 1 female worker, exposed to lead on average for 6 years. The systolic blood pressure in lead workers (101-160 mmHg, 124.4 ± 14.7 mmHg) was found to be significantly higher than in controls (97-134 mmHg, 115.4 ± 10.4 mmHg, p < 0.01) as was plasma norepinephrine (0.51 ± 0.1 μg/liter vs 0.24 ± 0.05 μg/liter, p < 0.01). The density of lymphocyte β₂-adrenergic receptors (B(max)) in lead-exposed workers was 86% lower than that in controls (0.15 ± 0.08 vs 1.08 ± 0.29 fmol/0.1 x 10⁶ cells; p < 0.01). The dissociation constants (K(d)) of [¹²⁵I]iodocyanopindolol were 93.6 ± 42.6 and 87.9 ± 42.7 pM in lead-exposed workers and controls, respectively. Multiple linear regression analysis showed that elevation of systolic pressure was closely related to (a) blood lead levels, (b) decreased β₂-adrenergic receptor density, and (c) increased plasma catecholamine levels in lead-exposed workers. Linear regression analysis revealed that both plasma norepinephrine levels and β₂-adrenoceptor density (B(max)) were highly correlated with both systolic blood pressures and blood lead levels in lead-exposed workers, and a highly significant negative correlation was found to exist between B(max) and plasma norepinephrine levels (r = -0.82, p < 0.001). These data therefore demonstrate that there is a close relationship between elevated plasma catecholamine levels, decreased β₂-adrenergic receptors, and elevated blood pressure in lead-exposed workers.