Reactivity of sympathetic nervous system in patients with fixed essential hypertension

ABSTRACT

The reactivity of different components of the sympathetic nervous system has been achieved through a number of physiologic and pharmacologic tests, in patients with fixed essential hypertension [FEH], and compared with those of the normotensive control subjects. Change of posture [standing], was used to study the whole baroreceptor reflex arc. The cold pressure test was used to test the discharge in the efferent sympathetic fibres. The reactivity of the alpha, and beta adrenergic receptors were studied through their responsiveness to infusions of nor-epinephrine and isoproternol respectively. Beta receptors activity was also investigated by the blocking effect of propranolol hydrochloride injection, through its cardiac slowing effect. The results of the study showed that patients with FEH have significant increase in both the efferent sympathetic fiber discharge [P < .05], and in the reactivity of alpha adrenergic receptors [P < 0.001] than in the normotensive control subjects: