Lactate and pyruvate are hormonally stimulated products of the Sertoli cell, which are essential for germ cell survival. The utility of measuring these products as indices of Sertoli cell function was examined using toxicants targeted to this cell type. Hence, 1,3-dinitrobenzene (1,3-DNB; 10(-6) - 10(-4) M), and mono-(2-ethylhexyl)phthalate (MEHP; 10(-8) - 10(-4) M) were tested in rat Sertoli cell cultures. Both compounds produced significant dose-related increases (maximally three- to fourfold) in lactate concentrations in the culture medium. Only 1,3-DNB produced significant dose-related increases (up to eight- to ninefold) in pyruvate concentrations. All increases occurred within 24 hr of exposure, with the earliest changes occurring within 1-2 hr. The specificity of the responses was examined by comparison with the nontoxic isomers, 1,2 and 1,4-DNB, and the parent compound of MEHP, di-(2-ethylhexyl) phthalate and its inactive metabolite, 2-ethylhexanol. None of these compounds showed significant effects on lactate or pyruvate production. The spermatocyte toxicant, ethylene glycol monomethyl ether (EGME), and its major metabolite, methoxyacetic acid (MAA), were also tested. EGME had no effect on lactate or pyruvate production, and MAA produced a decrease in lactate concentration only at the maximum dose employed (5 mM). These results show that dose-related increases in lactate production were only observed for the two Sertoli cell toxicants, and only for 1,3-DNB in the case of pyruvate production. Inactive isomers, metabolites, and germ cell toxicants did not produce these changes. Thus, lactate (and pyruvate) production by rat Sertoli cell cultures may be a sensitive index of altered function as induced by 1,3-DNB and MEHP.