Increased concentration ofcirculating calcitonin generelated peptide during normal humanpregnancy

Calcitonin generelated peptide isanextremely potentvasoactive peptide that causesprofound vasodilatation inman. Itsdistribution inperivascular nervessuggests that one ofits functions may betheregulation ofperipheral vascular tone.Pregnancy isa physiological condition inwhichthere aremajorhaemodynamic changes. Anincrease inplasma volume ofabout 40%necessitates changes inperipheral vascular tone.Ina crosssectional study plasma concentrations ofimmunoreactive calcitonin generelated peptide were measured throughout normal pregnancyandatfive tosevendayspostpartum.Calcitonin gene related peptide concentrations were significantly increased throughout pregnancy butfell after delivery. Calcitonin generelated peptide may participate inthephysiological regulation ofvasomotortoneinman. hadtaken anydrugs, apartfromiron andfolic acid supplements, for atleast three months. Allpregnancies were singleton andresulted in a full term delivery ofalive, healthy babyofappropriate weight. Fasting venousblood samples weretaken atabout 900am into cooled, heparinised tubes, andthe plasma was separated immediately. Thesamples werestored at- 20'Cuntil assayed. Controls-Twelve normal, female volunteers whowere notpregnant, mean age32-3(range 23-39) years,were usedascontrols. Noneofthese women wastaking anymedication. Methods-Plasma calcitonin gene related peptide was measured directly byradioimmunoassay4 withrabbit antiserum CC2/1raised against synthetic humancalcitonin generelated peptide conjugated tobovine albumin. The sensitivity was 05fmol/tube. Intra-assay andinterassay variations were6% and9%,respectively. Statistical analyses-Analysis ofvariance andtwotailed Student's ttest wereusedafter logtransformation tomakethedata distribution normal.