The influence of age and sex on cardiac, renal and caudal artery catecholamine content in spontaneously hypertensive (SHR) and Wistar Kyoto (WKY) rats.

Abstract

Noradrenaline (NA), adrenaline (A) and dopamine (DA) levels were measured in the heart, kidney and caudal artery of male and female SHR and WKY rats aged 6, 14 and 28 weeks, and the influence of strain, sex and age on catecholamine content determined. Levels of A were elevated in all three regions of SHR compared to WKY rats, independent of age and sex. This may represent increased A accumulation in sympathetic nerves resulting from the increased sympatho-adrenomedullary hyper-reactivity of the SHR strain. DA levels were also elevated in the heart and kidney of SHR rats, independent of sex and age. Na levels were lower in the heart of SHR rats, but this appeared to be partly a consequence of cardiac hypertrophy and partly due to strain difference between older male but not female rats. Thus a simple association between decreased cardiac NA levels and hypertension appeared unlikely. It is emphasised that further genetic studies of F2 backcross rats would be required to establish an etiological association between these differences in catecholamine levels and differences in blood pressure between the SHR and WKY strains.