Fig. 4.

Acute mean arterial pressure (MAP) at baseline and following amphetamine or saline injection. All amphetamine injections elevated MAP across all time points compared with all saline injections (*P < 0.05). However, the 1st amphetamine injection significantly elevated MAP above all other groups (#P < 0.05). This robust elevation in MAP was not observed during any subsequent amphetamine injections, indicating that rats developed tolerance to the robust hypertensive response elicited by amphetamine.