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

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Abstract
The stability of the saliva/plasma (SIP) concentration ratio of atrazine was determined under varying conditions of salivary flow rate and plasma concentration of atrazine in Sprague-Dawley rats. In the salivary flow study, whole saliva samples were collected at different salivary flow rates while the plasma concentration of atrazine was maintained at a steady-state level of approximately 150 μgll. In the plasma level study, whole saliva samples were collected at two steady-state plasma concentrations of atrazine (50 and 250 μgll), while salivary flow rate was maintained at a relatively constant level. In both studies, atrazine concentrations in whole saliva and arterial plasma demonstrated a consistent rela tionship, but salivary concentrations were always lower than those of arterial plasma. Linear regression analysis demonstrated that the SIP concentration ratio of atrazine was not significantly different for salivary flow rates ranging from 23 to 92 pLIminlkg body weight, and did not vary for atrazine plasma concentrations between 30 and 433 μglL. The SIP concentration ratio of atrazine was relatively constant throughout each experimen tal period (0.68 ± 0.7 and 0.70 ± 0.11 for salivary flow and plasma level studies, respec tively) and did not differ significantly between rats. When data from both studies were pooled, salivary concentrations were highly correlated with plasma concentrations (r2 = .94). It is concluded that under these experimental conditions, the stability of the SIP con centration ratio of atrazine is not affected by variations in salivary flow rate or atrazine plasma concentrations. The results from this study support the conclusion that atrazine salivary concentrations can be used to predict plasma levels of atrazine in rats.