We have previously demonstrated two different catecholaminergic patterns in genetic and experimental hypertension: a hyperdopaminergic state in spontaneously hypertensive (Okamoto) rats (SHR) and a hypernoradrenergic state in salt-sensitive Dahl rats. Plasma immunoreactive atrial natriuretic factor (IR ANF) concentrations increase in both models as a response to hypertension. To distinguish between the genetic and acquired components of these abnormalities, we measured adrenal dopamine-β-hydroxylase (DβH) activity and coeliac ganglionic atrial natriuretic factor (ANF) like immunoreactivity in the two animal strains. While adrenal DβH activity was increased in Dahl S rats, it was diminished in SHR in the prehypertensive as well as in the hypertensive stages. In the hypertensive stage, the ANF-like immunoreactivity in the coeliac ganglia was lower in the Dahl S group but higher in SHR than in their respective normotensive controls; there were no changes in these animals when they were prehypertensive. Differences in D 1/2 bH activity, which determines the fine tuning of sympathoadrenomedullary catecholamine synthesis may account for the inheritance of mechanisms resulting in salt-sensitive hypertension (as in SHR) or salt-dependent hypertension (as in Dahl salt-sensitive rats). In contrast, plasma IR ANF concentrations may reflect a defense mechanism against hypertension. However ANF-like immunoreactivity in coeliac ganglia does not follow its plasma concentrations and changes in different directions in the two hypertensive strains; it may reflect a neuromodulatory function of ANF in the ganglionic neurotransmission and different implications of this role of ANf in the two hypertensive models.
ASJC Scopus subject areas
- Physiology (medical)