Nonlinear (top) and linear (bottom) regression analysis of the baroreflex correlating mean arterial pressure (MAP) and heart rate (HR) values in adolescent animals subjected to treatment for 10 consecutive days with testosterone and cocaine alone and in combination.

Symbols on sigmoid curves (top) indicate the respective BP50. Circles represent the mean and bars the SEM on linear regression curves (bottom). veh – vehicle, test - testosterone and coc – cocaine. Increase or decrease in the MAP was induced by intravenous infusion of phenylephrine and sodium nitroprusside, respectively.