PRENATAL MALNUTRITION-INDUCED CHANGES IN BLOOD-PRESSURE - DISSOCIATION OF STRESS AND NONSTRESS RESPONSES USING RADIOTELEMETRY

A link between prenatal malnutrition and hypertension in human populat ions has recently been proposed. Rat models of prenatal malnutrition h ave provided major support for this theory on the basis of tail-cuff m easurements. However, this technique requires restraint and elevated t emperature, both potential sources of stress. To determine the effect of prenatal protein malnutrition on blood pressure under nonstress con ditions, 24-hour radiotelemetric measurements were taken in the home c age. Male rats born to dams fed a 6% casein diet for 5 weeks before ma ting and throughout pregnancy were studied in early adulthood (from 96 days of age). During the waking phase of their cycle but not the slee p phase, prenatal malnutrition gave rise to small but significant elev ations of diastolic blood pressure and heart rate compared with well-n ourished controls. Direct effects of stress on blood pressure response s were determined in a second experiment using an olfactory stressor. Prenatally malnourished rats showed a greater increase in both systoli c and diastolic pressures compared with well-nourished controls during the first exposure to ammonia. A different pattern of change of cardi ovascular responses was also observed during subsequent presentations of the stressor. These findings of a small baseline increase in diasto lic pressure consequent to prenatal malnutrition, but an augmented ele vation of both systolic and diastolic pressures after first exposure t o stress, suggest the need to reevaluate interpretation of the large e levations in blood pressure previously observed in malnourished animal s using the stressful tail-cuff procedure.