CORRESPONDENCE OF SALIVARY AND PLASMA-CONCENTRATIONS OF ATRAZINE IN RATS UNDER VARIABLE SALIVARY FLOW-RATE AND PLASMA-CONCENTRATION

The stability of the saliva/plasma (S/P) concentration ratio of atrazi ne was determined under varying conditions of salivary flow rate and p lasma concentration of atrazine in Sprague-Dawley rats. In the salivar y flow study, whole saliva samples were collected at different salivar y flow rates while the plasma concentration of atrazine was maintained at a steady-state level of approximately 150 mu g/L. in the plasma le vel study, whole saliva samples were collected at two steady-state pla sma concentrations of atrazine (50 and 250 mu g/L), while salivary flo w rate was maintained at a relatively constant level. In both studies, atrazine concentrations in whole saliva and arterial plasma demonstra ted a consistent relationship, but salivary concentrations were always lower than those of arterial plasma. Linear regression analysis demon strated that the S/P concentration ratio of atrazine was not significa ntly different for salivary flow rates ranging from 23 to 92 mu L/min/ kg body weight, and did not vary for atrazine plasma concentrations be tween 30 and 433 mu g/L. The S/P concentration ratio of atrazine was r elatively constant throughout each experimental period (0.68 +/- 0.1 a nd 0.70 +/- 0.11 for salivary flow and plasma level studies, respectiv ely) and did not differ significantly between rats. When data from bot h studies were pooled, salivary concentrations were highly correlated with plasma concentrations (r(2) = .94). It is concluded that under th ese experimental conditions, the stability of the S/P concentration ra tio of atrazine is not affected by variations in salivary flow rate or atrazine plasma concentrations. The results from this study support t he conclusion that atrazine salivary concentrations can be used to pre dict plasma levels of atrazine in rats.