Maternal Separation (MS) enhances angiotensin II (Ang II)‐induced hypertension in Dahl rats fed a high salt diet

Abstract

Previously, we showed that MS, a model of early life stress, enhances the response to hypertensive stimuli in a non‐salt sensitive rat strain. The aims of this study were to test whether MS in Dahl salt‐sensitive (DS) rats exaggerates: 1) the acute or chronic behavioral stress response, or, 2) AngII and/or high salt diet‐induced hypertension. MS was performed in male DS rats by separating about half of the pups from the dam 3 hr a day from days 2–14 after birth. Undisturbed littermates served as controls (C). Rats were implanted with telemetry transmitters (10 weeks of age, n=4–6) and allowed to recover. Mean arterial pressure (MAP) was not different between C and MS rats at baseline (118±1 vs. 120±2 mmHg). Acute air jet stress‐induced pressor response measured as area under the curve (AUC) was not different in C and MS rats. AUC due to chronic restraint stress was not different in C and MS rats as well. Separate groups of rats were fed either a high salt diet (HSD, 4%NaCl), infused with AngII (200 ng/kg/min) or infused with AngII + HSD for one week. MAP was not different in C and MS rats fed a HSD (176±5 vs. 163±7 mmHg). AngII‐induced hypertension was not different in C and MS rats (146±4 vs. 150±1 mmHg). AngII+HSD increased MAP in MS rats compared to C rats (167±5 vs. 152±2 mmHg, respectively, ptime=<0.05, pseparation= <0.05 and pinteraction= <0.05). We conclude that MS exacerbates AngII‐induced hypertension in the presence of HSD in DS rats.