Anteroposterior distribution of AT(1) angiotensin receptors in caudal brainstem cardiovascular regulatory centers of the rat.

The purpose of this study is to investigate the density of AT1 receptors in the RVLM, CVLM and DMM (Dorsomedial medulla) regions of the rats. The authors used adult female retired breeder Wistar rats to evaluate AT1 receptor binding along a 2.7mm length of medulla.   They used receptor binding autoradiography to visualize AT1 receptor binding in the above mentioned regions. The significant finding from the present study is that they showed AT1 receptor binding in a rostro-caudal plane extending from CVLM to RVLM. The density of AT1 receptor is fairly constant along the rostro-caudal extent.  They found that AT1 receptor binding density (Bmax) was lower in CVLM and RVLM than DMM.  The dissociation constant (KD) of AT1 binding sites in the RVLM and CVLM is lower indicating higher affinity i.e. neurons in the RVLM and CVLM are more sensitive to Ang II compared to DMM.

-Madhan