Premium
Carotid Chemoreceptor Desensitization Improves Baroreflex Control of Blood Pressure During Hypoxia in Humans
Author(s) -
Mozer Michael,
Joyner Michael,
Curry Timothy,
Limberg Jacqueline
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.1060.4
Subject(s) - chemoreceptor , carotid body , hypoxia (environmental) , baroreflex , dopamine , heart rate , blood pressure , anesthesia , peripheral chemoreceptors , baroreceptor , medicine , endocrinology , saline , reflex , chemistry , stimulation , receptor , organic chemistry , oxygen
There are known interactions between the chemoreflex and baroreflex. The purpose of the present investigation was to examine the contribution of the carotid body chemoreceptors to changes in baroreflex control of blood pressure with exposure to hypoxia. Low‐dose dopamine blunts carotid body afferent activity and can thus be used to examine the contribution of the carotid chemoreceptors to reflex responses during hypoxia. Hypothesis Spontaneous cardiac baroreflex sensitivity (scBRS) will be reduced with hypoxia and this effect will be blunted when the carotid chemoreceptors are desensitized with low‐dose dopamine. Methods Seven subjects (4M/3F) completed 2 visits randomized to IV dopamine (individualized dose shown to result in a nadir hypoxic ventilatory response, 1‐4 μg/kg/min) or placebo (saline). Subjects were exposed to 5‐min normoxia (99±0% SpO2), followed by 5‐min hypoxia (83±2%SpO2). Blood pressure (intra‐arterial catheter) and heart rate (ECG) were measured continuously and sCBRS was assessed by spectrum analysis. The relative (%) change in sCBRS with hypoxia [(Hypoxia‐Normoxia)/Normoxia x 100)] was compared between dopamine and placebo. Results scBRS was reduced with hypoxia (saline p<0.01; dopamine p<0.01). The fall in scBRS with hypoxia was blunted with dopamine (saline: ‐58±7 %, dopamine: ‐42±9 %, p=0.02). Conclusion These data are consistent with a reduction in scBRS with chemoreceptor activation. Furthermore, we show this effect is partially mediated by the carotid body chemoreceptors, given the fall in scBRS is attenuated when the chemoreceptors are desensitized with low‐dose dopamine. Funding NIH DK090541 (Joyner)