APLNR and Hypertension: The levels of apelinergic gene expression in some tissues however are altered in rodent models of hypertension, e.g. the cardiac apelinergic system is downregulated in the Dahl salt-sensitive rat [41], and decreased aplnr and apln levels are seen in the heart and aorta of spontaneously hypertensive rats (SHR) compared to normotensive Wistar Kyoto (WKY) rats [42], while APJ and apelin mRNA and protein are upregulated in the SHR PVN [8].