Baroreflex response with iron deficiency: a comparison of steady‐state and ramp techniques

We have demonstrated that the baroreflex is altered by iron deficiency (ID), and that both sympathetic and parasympathetic efferents are affected (EB2006, EB2005). In those studies, we used the “ramp” technique, in which a continuous infusion alters blood pressure (BP), and an afferent signal comes mainly from arterial baroreceptors. The objective of this study was to determine whether non‐arterial baroreceptors are also altered by ID. To do this, we employed the “steady‐state” baroreflex protocol, in which BP is altered, but held steady for 90 s, with HR measured during the final 30 s. CD rats (Harlan) were put on an ID or control (C) diet for 4 weeks; ID was confirmed by microhematocrit (p<0.05). One femoral artery and both femoral veins were catheterized; rats recovered for 1 d. Phenylephrine and nitroprusside were infused intravenously in bolus volumes to alter BP across a broad range; BP was held steady for 90 s by small subsequent infusions. Further experiments are continuing at time of abstract writing. However, a preliminary data analysis (n=9) has been completed, and indicates that, in sharp contrast to our “ramp” technique experiments, the steady‐state baroreflex is not altered by ID. If confirmed by further experimental repetitions, we conclude that ID alters arterial, but not non‐arterial, afferent components of the baroreflex. Supported by the Wyoming NIH INBRE Grant (LC4090).