Congener-specific effects of PCBs on contractions of pregnant rat uteri.
Both increased and decreased gestation lengths have been reported following exposures to polychlorinated biphenyl (PCB) mixtures and congeners. Because oscillatory uterine contractions are essential for parturition, we hypothesized that the disparate findings on gestation length may be the result of distinct PCB congener-specific actions on oscillatory uterine contractions. This study examined the acute effects of PCB congeners on isometric contractions of isolated pregnant uteri and the structure-activity relationship for individual congeners. After cumulative exposure to individual PCB congeners (0.5 microM to 150 microM), oscillatory contractions were: 1) not altered by 2,4,5,2',4',5'-hexachlorobiphenyl, 3,4,5,3',4'-pentachlorobiphenyl, or 3,4,3',4'-tetrachlorobiphenyl; 2) significantly inhibited by 4-hydroxy-2',4',6'-trichlorobiphenyl; and 3) markedly increased by 2,4,6-trichlorobiphenyl and 2,4,2',4'-tetrachlorobiphenyl, when compared to solvent controls. The uteri were more sensitive to PCB congeners with ortho-substituted light chlorination than those highly chlorinated, or those interacting with the Ah-receptor.
Tsai
M L
ML
Department of Environmental and Industrial Health, University of Michigan, Ann Arbor 48109-2029, USA.
Webb
R C
RC
Loch-Caruso
R
R
D000704:Analysis of Variance; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013329:Structure-Activity Relationship; D014590:Uterine Contraction / Q000187:drug effects*
C102834:2,4,6-trichlorobiphenyl; C035976:2,4,2',4'-tetrachlorobiphenyl; D011078:Polychlorinated Biphenyls; C023035:3,4,5,3',4'-pentachlorobiphenyl; C014024:2,4,5,2',4',5'-hexachlorobiphenyl