1. Seven latent hypertensive patients and seven matched controls were subjected to standardized mental stress and orthostatic provocation.
2. Mental stress increased blood pressure by approximately 25%, heart rate by 25 beats/min, plasma glycerol by 50% and plasma cyclic AMP by 25% in both groups. Plasma glucose and renin activity were unchanged. Plasma noradrenaline and adrenaline were essentially unchanged during stress.
3. There was an insignificant tendency towards higher noradrenaline levels in latent hypertensive subjects and two of these subjects displayed an exaggerated noradrenaline response to standing.
4. Our results indicate that the physiological responses to mental stress are caused by selective neuronal activation, rather than by generalized sympatho-adrenal activation. Latent hypertension does not seem to be associated with adrenergic hyperactivity or receptor supersensitivity, except possibly in individual cases.