Abstract
ATP-sensitive K+ (KATP) channel subunits Kir6.1, Kir6.2, SUR1, SUR2A, and SUR2B in the rat pituitary gland were first investigated by RT-PCR assay and immunohistochemical staining. The results of RTPCR analysis showed that the rat pituitary gland expressed the five KATP channel subunits mentioned above. Immunohistochemical staining showed that these KATP channel subunits were widely localized in the anterior lobe, intermediate lobe, and posterior lobe at different intensities. Immunofluorescence double and triple staining showed that these KATP channel subunits colocalized with cells containing adrenocorticotropic hormone (ACTH) in the anterior lobe of the pituitary gland. Interestingly, neither Kir6.1 nor Kir6.2 colocalized with cells containing prolactin (PRL), follicular stimulating hormone (FSH), and growth hormone (GH). These results suggest that ACTH cells contain four types of KATP channels: Kir6.1/SUR2A, Kir6.2/SUR2A, Kir6.1/SUR2B, and Kir6.2/SUR2B. KATP channels may play some important roles in ACTH cells in the pituitary gland. The different compositions of KATP channel subunits in corticotrophs but not in the PRL, FSH, and GH cells might be due to the different metabolic situations of these cells. Key words: ATP-sensitive K+ channel; Kir6.x; SUR2; immunohistochemistry; pituitary gland; rat
