Effects of gender and age on the cardiac baroreceptor reflex in hypertension

The present study examined whether alterations in the cardiac baroreceptor reflex in hypertension may be a function of constitutional differences asso ciated with gender and age. These hypotheses were tested using a cross-sect ional design that compared 20 normotensive and 21 hypertensive men and wome n of varying age for differences in baroreceptor reflex sensitivity and res ponse latency for heart rate, obtained using a modified bolus phenylephrine (Oxford) method. Relative to their respective normotensive controls, baroreceptor reflex sen sitivity was reduced in hypertensive men, but not in hypertensive women. Am ong normotensive subjects, men had greater baroreceptor reflex sensitivity than women. Independent from the effects associated with differences in blo od pressure, age was not a significant predictor of reduction in barorecept or reflex sensitivity. However, a combination of high blood pressure and ol der age was associated with a significant increase in baroreceptor reflex r esponse time. In summary, gender and aging interacted with hypertension to alter two different aspects of the baroreceptor reflex. These results provi de a preliminary indication that a decline in arterial baroreflex sensitivi ty may be more specific to hypertension in men than in women. Prolongation in baroreflex response latency in older hypertensive subjects also suggeste d that aging and hypertension may have a synergistic effect on cardiac para sympathetic function.