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The Dahl salt-sensitive (DS) and salt-resistant (DR) rat lines were selectively bred to show opposite genetically determined blood pressure responses to excess sodium chloride ingestion. These animals have provided significant anatomical, physiological, and biochemical data concerning the pathological mechanisms of experimental hypertension. Research is also being conducted to determine the relevance of psychobiological and behavioral variables in these two lines. The rationale for the selection and maintenance of the Dahl model and the physiological, biochemical, and behavioral characteristics which distinguish DS and DR rats are presented. Although originally developed for the study of salt-induced hypertension, special attention is given to the application of this animal model in behavior genetic research, stressing its inherent advantages and limitations. The use of the Dahl model in psychobiological studies and the utility of the model for future behavioral, genetic, and psychophysiological research are also detailed.

The Dahl selected rat lines, one susceptible to salt-induced hypertension (DS) and the other resistant to salt-induced hypertension (DR), were exposed to filtered air, 0.4, 1.4, or 4.0 ppm acrolein for 6 h/day, 5 days/week for 62 days. All of the DS rats exposed to 4.0 ppm acrolein died within the first 11 days, while 60% of the DR animals survived the duration of the study. Neither dose dependent blood pressure changes nor altered behavioral characteristics were evident in either rat strain following acrolein exposure. Exposure to 4.0 ppm acrolein increased the level of several serum enzymes in the DR rats which survived. This concentration of acrolein also led to pulmonary edema and a significant increase in lung connective tissue in these animals. There was a marked difference in the pulmonary pathology observed in DS and DR rats exposed to 4.0 ppm acrolein. The lungs of moribund DS rats exhibited severe airway epithelial necrosis with edema and hemorrhage, while surviving DR rats primarily showed a proliferative change. Following exposure to 0.4 and 1.4 ppm acrolein, both rat lines displayed similar pathologic changes. Epithelial hyperplasia and/or clusters of macrophages were usually found near terminal bronchiolar areas. These findings suggest that further investigation of the physiopathologic sensitivity of the DS rat line may elucidate a model for investigating the underlying characteristics of stress susceptible populations.