The spontaneously hypertensive rat (SHR) is used as a model for attention-deficit hyperactivity disorder (ADHD), since it has behavioural characteristics that resemble the behavioral disturbances of ADHD, namely hyperactivity, failure to sustain attention, and impulsiveness. The aim of this study was to establish whether N-methyl-D-aspartate (NMDA) receptor function was altered in barrel cortex slices of 4- to 6- week-old SHR compared to their normotensive Wistar-Kyoto (WKY) control rats. The barrel cortex was dissected from brain slices corresponding to antero-posterior coordinates 8.7-4.8 mm with reference to the Paxinos and Watson (1986) atlas and divided into rostral, middle, and caudal regions. 45Ca2+ uptake was stimulated by incubating test slices in buffer containing 100 microM NMDA for 2 min at 35 degrees C. Total 45Ca2+ uptake into the entire barrel cortex as well as uptake into all regions of SHR barrel cortex was lower compared to WKY. Basal uptake into the entire barrel cortex as well as uptake into rostral and caudal regions of SHR barrel cortex was lower than WKY but basal uptake into the middle region was the same for both strains. There was no difference between SHR and WKY in NMDA-stimulated 45Ca2+ uptake into barrel cortex slices except for significantly lower NMDA-stimulated uptake into the middle region of SHR barrel cortex compared to WKY. These findings suggest that calcium metabolism is disturbed in the somatosensory cortex of SHR but that NMDA receptor function is not altered.