Effect of dietary calcium on renal prostaglandins.
The present study was designed to clarify the possible role of renal prostaglandins (PGs) on blood pressure (BP) regulation during calcium (Ca) restriction or supplementation. Twelve normotensive women with a mean age of 21.2 years participated in the study. After 1 week of normal Ca intake (mean +/- SE, 536 +/- 2 mg/day), a low-Ca diet (163 +/- 1 mg/day) was given for a further 1 week. Additional asparagine Ca (3 g as Ca/day) was also given to half of the subjects. BP, heart rate, and serum total and ionized Ca concentrations were measured at the end of each period. Levels of Ca, sodium, PGE2, 6-keto-PGF1 alpha and thromboxane (TX) B2 excreted into urine were also determined. The plasma level of ionized Ca was significantly increased without any change in total Ca in both groups. Low and high Ca intake decreased and increased urinary Ca excretion by 28% and 56%, respectively. BP was not altered after Ca deprivation or loading. However, urinary PGE2 excretion was significantly augmented from 668.9 +/- 68.1 to 959.7 +/- 183.1 ng/day by Ca loading, whereas Ca deprivation decreased PGE2 excretion (695.4 +/- 108.1 to 513.2 +/- 55.2 ng/day). No changes were observed in 6-keto-PGF1 alpha or TXB2 urinary excretion. These results suggest that renal PGE2 synthesis is stimulated or decreased by 1-week Ca loading or deprivation, indicating a possible antihypertensive role of renal PGE2 during high-Ca intake in hypertensives.
Katayama
S
S
Fourth Department of Medicine, Saitama Medical School, Japan.
Maruno
Y
Y
Itabashi
A
A
Inaba
M
M
Akabane
S
S
Tanaka
K
K
Tanaka
K
K
Shibuya
M
M
Kawazu
S
S
Ishii
J
J
D015121:6-Ketoprostaglandin F1 alpha / Q000652:urine; D000328:Adult; D000959:Antihypertensive Agents / Q000097:blood / Q000652:urine; D001794:Blood Pressure; D002136:Calcium, Dietary / Q000097:blood / Q000378:metabolism* / Q000652:urine; D015232:Dinoprostone / Q000652:urine; D005260:Female; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D011453:Prostaglandins / Q000652:urine*; D012964:Sodium / Q000652:urine; D013929:Thromboxane B2 / Q000652:urine
D000959:Antihypertensive Agents; D002136:Calcium, Dietary; D011453:Prostaglandins; D013929:Thromboxane B2; D015121:6-Ketoprostaglandin F1 alpha; D012964:Sodium; D015232:Dinoprostone