ABSTRACT: Dietary benzoic acid (BA) supplemen-
tation causes a pronounced reduction in urinary pH
but only small changes in blood pH. The present study
aimed to investigate the portal absorption profile, he-
patic metabolism of BA, and renal excretion of hippuric
acid (HA) underlying the relatively small impact of BA
on systemic acid-base status. Eight growing pigs (BW =
63 ± 1 kg at sampling) fitted with permanent indwell-
ing catheters in the abdominal aorta, hepatic portal
vein, hepatic vein, and mesenteric vein were allocated
to 4 sampling blocks and randomly assigned to control
(CON; nonsupplemented diet) or BA supplementation
(B; control diet + 1% BA top-dressed). Feed intake was
restricted to 3.6% of BW and the ration divided into 3
equally sized meals offered at 8-h intervals. Blood pH
(7.465 and 7.486 ± 0.004) and urinary pH (4.99 and
7.01 ± 0.09) were less (P = 0.03 and P < 0.01) in B
compared with CON. The arterial concentration, net
portal flux, and net hepatic uptake of BA increased (P
< 0.01) in B compared with CON. The net portal flux
of BA increased (P < 0.01) after feeding with B, but
remained positive (P < 0.01) at all sampling times (n
= 8). Recovery of dietary BA as increased net portal
flux and hepatic uptake of BA was 87 ± 5% and 89 ±
15%, respectively. The recovery of dietary BA as uri-
nary excretion of BA and HA was 0.08 ± 0.02% and
85 ± 7%, respectively. It is concluded that the small
impact of BA supplementation on systemic acid-base
status was caused by a protracted BA absorption and
efficient hepatic extraction and glycine conjugation in
combination with efficient renal clearance of HA. To-
gether, these physiological mechanisms prevented ma-
jor BA and HA accumulation in body fluids
ABSTRACT: Dietary benzoic acid (BA) supplemen-tation causes a pronounced reduction in urinary pH but only small changes in blood pH. The present study aimed to investigate the portal absorption profile, he-patic metabolism of BA, and renal excretion of hippuric acid (HA) underlying the relatively small impact of BA on systemic acid-base status. Eight growing pigs (BW = 63 ± 1 kg at sampling) fitted with permanent indwell-ing catheters in the abdominal aorta, hepatic portal vein, hepatic vein, and mesenteric vein were allocated to 4 sampling blocks and randomly assigned to control (CON; nonsupplemented diet) or BA supplementation (B; control diet + 1% BA top-dressed). Feed intake was restricted to 3.6% of BW and the ration divided into 3 equally sized meals offered at 8-h intervals. Blood pH (7.465 and 7.486 ± 0.004) and urinary pH (4.99 and 7.01 ± 0.09) were less (P = 0.03 and P < 0.01) in B compared with CON. The arterial concentration, net portal flux, and net hepatic uptake of BA increased (P < 0.01) in B compared with CON. The net portal flux of BA increased (P < 0.01) after feeding with B, but remained positive (P < 0.01) at all sampling times (n = 8). Recovery of dietary BA as increased net portal flux and hepatic uptake of BA was 87 ± 5% and 89 ± 15%, respectively. The recovery of dietary BA as uri-nary excretion of BA and HA was 0.08 ± 0.02% and 85 ± 7%, respectively. It is concluded that the small ผลกระทบของ BA แห้งเสริมในระบบกรดฐาน สถานะที่เกิดจากการดูดซึมบายืดเยื้อ และ ประสิทธิภาพตับสกัดและ glycine conjugation ใน ร่วมกับมีประสิทธิภาพ renal เคลียร์ของ HA การ-gether กลไกเหล่านี้สรีรวิทยาป้องกันม้า-หลังบาและฮาสะสมในของเหลวของร่างกาย
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