Deletion of proton-sensing receptor GPR4 associates with lower blood pressure and lower binding of angiotensin II receptor in SFO.
Diets rich in grains and meat and low in fruits and vegetables (acid-producing diets) associate with incident hypertension, whereas vegetarian diets associate with lower blood pressure (BP). However, the pathways that sense and mediate the effects of acid-producing diets on BP are unknown. Here, we examined the impact of the deletion of an acid sensor GPR4 on BP. GPR4 is a proton-sensing G protein-coupled receptor and an acid sensor in brain, kidney, and blood vessels. We found that GPR4 mRNA was higher in subfornical organ (SFO) than other brain regions. GPR4 protein was abundant in SFO and present in capillaries throughout the brain. Since SFO partakes in BP regulation through the renin-angiotensin system (RAS), we measured BP in GPR4-/- and GPR4+/+ mice and found that GPR4 deletion associated with lower systolic BP: 87 ± 1 mmHg in GPR4-/- (n = 35) vs. 99 ± 2 mmHg (n = 29) in GPR4+/+; P < 0.0001, irrespective of age and sex. Angiotensin II receptors detected by125I-Sarthran binding were lower in GPR4-/- than GPR4+/+ mice in SFO and in paraventricular nucleus of hypothalamus. Circulating angiotensin peptides were comparable in GPR4-/- and GPR4+/+ mice, as were water intake and excretion, serum and urine osmolality, and fractional excretion of sodium, potassium, or chloride. A mild metabolic acidosis present in GPR4-/- mice did not associate with elevated BP, implying that deficiency of GPR4 may preclude the effect of chronic acidosis on BP. Collectively, these results posit the acid sensor GPR4 as a novel component of central BP control through interactions with the RAS.
Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina.|Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; and.
Xuming
X
Sun
Department of Surgery, Wake Forest School of Medicine, Winston-Salem, North Carolina.|Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; and.
Ellen
E
Tommasi
Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina.
Doris
D
Molina
Department of Psychiatry and Behavioral Neuroscience, College of Medicine, University of Cincinnati, Cincinnati, Ohio.
Renu
R
Sah
Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina.|Department of Surgery, Wake Forest School of Medicine, Winston-Salem, North Carolina.|Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; and.
K Bridget
KB
Brosnihan
Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina.|Department of Surgery, Wake Forest School of Medicine, Winston-Salem, North Carolina.|Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; and.
Debra
D
Diz
Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina; snpetrov@wakehealth.edu.|Department of Internal Medicine, Section on Gerontology and Geriatric and Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, North Carolina.|Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; and.
Snezana
S
Petrovic
D000818:Animals; D001794:Blood Pressure / Q000235:genetics*; D005260:Female; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D044139:Receptor, Angiotensin, Type 2 / Q000235:genetics / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics* / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000502:physiology*; D013356:Subfornical Organ / Q000378:metabolism*
C517811:GPR4 protein, mouse; D044139:Receptor, Angiotensin, Type 2; D043562:Receptors, G-Protein-Coupled
RAS; acid sensor; acid-producing diets
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