EFFECTS OF COLD PRESSOR TEST ON CIRCULATING ATRIAL NATRIURETIC PEPTIDE-99-126 (ANP) IN PATIENTS WITH RAYNAUDS-PHENOMENON AND INFLUENCE OF TREATMENT WITH MAGNESIUM-SULFATE AND NIFEDIPINE

The effect of a standardized cold pressure test (CPT) on the venous co ncentration of immunoreactive atrial natriuretic peptide (ir ANP) was studied in 12 females with primary Raynaud's phenomenon (PRP) and 12 f emale age-matched controls. The test was performed at the end of three stages. During the first stage no medication was given. During the se cond stage a magnesium infusion was given. After fourteen days of medi cation with a calcium antagonist (Nifedipine) the third stage of the s tudy was performed. The venous irANP increased significantly (P<0.05) 10 min after the start of the CPT both in the PRP group and in the con trol group (136+/-39 to 159+/-54 and 153+/-45 to 179+/-40 pg ml-1, giv en as mean and SD). Baseline irANP did not change in the PRP group aft er treatment with magnesium or nifedipine. In the control group nifedi pine treatment significantly (P<0.01) lowered venous irANP compared to the no treatment or magnesium sulphate infusion stages (128+/-31 vs. 153+/-45 and 160+/-41 pg ml-1). After the CPT in both PRP group and co ntrol group the venous irANP did not increase either during magnesium sulphate infusion or nifedipine treatment. In conclusion the study has demonstrated that a standardized CPT results in a delayed increase in irANP in venous plasma and that magnesium sulphate infusion and nifed ipine treatment prevent this increase. Furthermore, our data do not su ggest a role for irANP in the symptomatology of primary Raynaud's phen omenon.