Hypertensive and Normal Pregnancy--Calcium Metabolism and Renin-Angiotensin - SCOR in Hypertension

Hypertension Clinical Trial

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00005456
• Other study ID #: 4900
• Secondary ID: P50HL018323
• Status: Completed
• Phase: N/A
• First received: May 25, 2000
• Last updated: May 12, 2016
• Start date: December 1990
• Est. completion date: November 1995

Study information

• Verified date: March 2005
• Source: National Heart, Lung, and Blood Institute (NHLBI)
• Contact: n/a
• Is FDA regulated: No
• Health authority: United States: Federal Government
• Study type: Observational

Clinical Trial Summary

To study calcium metabolism and the renin-angiotensin system in hypertensive and normal pregnancy.

Description:

BACKGROUND:

Beginning in Fiscal Year 1975, the multidisciplinary SCOR examined causes, consequences, and treatments of human hypertension. A central theme was the renal basis for human hypertension. The subproject on calcium metabolism and the renin-angiotensin system in hypertensive and normal pregnancy began in December, 1990.

DESIGN NARRATIVE:

A longitudinal study was performed on normal pregnant women and women with chronic hypertension who had a high incidence of superimposed preeclampsia. In a previous study, the investigators had demonstrated that preeclampsia was associated with reduced urinary excretion of calcium and with lower plasma renin activity (PRA) compared with normal pregnancy. The goal of the investigators was to identify the metabolic and cellular basis for these alterations in calcium homeostasis and in the renin angiotensin system. They tested two hypotheses. The first hypothesis was that diminished placental and/or renal production of 1,25-dihydroxyvitamin D, leading to lower serum calcium, higher parathyroid hormone, and increased renal tubular reabsorption of calcium, was the metabolic basis for hypocalciuria in preeclampsia. The second hypothesis was that lower PRA in preeclampsia was due to systemic and renal vasoconstriction with hypertension and diminished natriuresis.

Serial measurements of 1,25-dihydroxyvitamin D, parathyroid hormone, serum ionized calcium, PRA, estradiol and progesterone, and urinary calcium and electrolytes were obtained, particularly at the onset of preeclampsia. Acute renal hemodynamic studies were also performed in women with preeclampsia and in gestational age matched normals. The studies investigated the relationships among glomerular filtration rate, renal blood flow, parathyroid hormone, vitamin D, atrial natriuretic factor, renin, estradiol and progesterone, and sodium and calcium excretion during infusion of inulin and PAH with either saline or calcium chloride.

Intracellular free calcium concentration in platelets and lymphocytes of pregnant women participating in longitudinal and acute renal hemodynamic studies were also measured. Basal and stimulated (with angiotensin II, ionomycin and thrombin), intracellular free calcium concentrations were compared in normal and hypertensive pregnant women and correlated with calcium regulatory hormones, plasma renin activity and hypertension.

The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 0
• Est. completion date: November 1995
• Accepts healthy volunteers: No
• Gender: Male
• Age group: N/A to 100 Years
• Eligibility: No eligibility criteria

Study Design

N/A

Related Conditions & MeSH terms

• Cardiovascular Diseases
• Eclampsia
• Heart Diseases
• Hypertension
• Pre-Eclampsia

Locations

Country	Name	City	State
n/a

Sponsors (1)

Lead Sponsor	Collaborator
National Heart, Lung, and Blood Institute (NHLBI)

References & Publications (5)

August P, Mueller FB, Sealey JE, Edersheim TG. Role of renin-angiotensin system in blood pressure regulation in pregnancy. Lancet. 1995 Apr 8;345(8954):896-7. — View Citation

Baylis C, Beinder E, Sütö T, August P. Recent insights into the roles of nitric oxide and renin-angiotensin in the pathophysiology of preeclamptic pregnancy. Semin Nephrol. 1998 Mar;18(2):208-30. Review. — View Citation

Blank SG, Helseth G, Pickering TG, West JE, August P. How should diastolic blood pressure be defined during pregnancy? Hypertension. 1994 Aug;24(2):234-40. — View Citation

Hojo M, August P. Calcium metabolism in normal and hypertensive pregnancy. Semin Nephrol. 1995 Nov;15(6):504-11. Review. — View Citation

Sealey JE, Itskovitz-Eldor J, Rubattu S, James GD, August P, Thaler I, Levron J, Laragh JH. Estradiol- and progesterone-related increases in the renin-aldosterone system: studies during ovarian stimulation and early pregnancy. J Clin Endocrinol Metab. 1994 Jul;79(1):258-64. — View Citation