Peripheral Chemoreceptors Contribute Significantly to Hypertension in Spontaneously Hypertensive Rats (SHR)

Abstract

In carotid body glomus cells of young pre hypertensive SHR the overexpression of acid sensing ion channels increases their pH sensitivity and is associated with increased sympathetic nerve activity (Tan et al., Circ. Res. 2010). Here we tested the hypothesis that early resection of the carotid bodies might reduce hypertension in SHR. Under anesthesia both carotid bodies were resected (CBX) in young (<5 weeks) SHR and in their normotensive control WKY. Arterial blood pressure (BP) recorded using a tail cuff twice a week over a 5 month period was lower in SHR with CBX than in sham‐operated SHR (p<0.05 ANOVA). The 24 hour intra‐arterial BP recordings in awake rats at 23 weeks of age are below. Systolic BP (mmHg) Mean BP (mmHg) Sham CBX Sham CBX WKY 149±5 (n=5) 146±6 (n=6) 120±5 119±7 SHR 239±6* (n=10) 202±8*† (n=9) 185±3* 159±6*† p<0.05 (SHR vs. WKY) p<0.05 (CBX vs. Sham) Compared to WKY, the mean BP was 65±3 mmHg higher in SHR‐Sham and only 40±6 mmHg higher in SHR‐CBX. Under anesthesia ventilatory and renal nerve activity responses to chemoreceptor stimulation were measured. The left ventricular (LV) weight of SHR‐Sham (1.04±0.03 gm) was significantly greater (p<0.002) than that of SHR‐CBX (0.92±0.01) and WKY (0.91±0.01).ConclusionThe contribution of the hypersensitive peripheral chemoreceptors to the increase in mean BP in SHR is estimated to be 38% and may account for most of the LV hypertrophy. (NIH/HL14388)