ORIGINAL ARTICLES   

International Angiology 2000 December;19(4):351-3

Copyright © 2001 EDIZIONI MINERVA MEDICA

language: English

Seasonal variation in plasma levels of endothe lin-1 and nitric oxide

McLaren M., Kirk G., Bolton-Smith C., Belch J. J. F.

From the Departments of Medicine and Cardiovascular Epidemiology Ninewells Hospital and Medical School, Dundee, Scotland, UK

Background. There is a sea­son­al vari­a­tion in the inci­dence of ­stroke and cor­o­nary heart dis­ease with admis­sions to hos­pi­tal being high­er in the cold­er ­months of the year. The mech­a­nism where­by this win­ter prev­a­lence of vas­cu­lar dis­ease ­occurs is still not fully under­stood. The aim of our study was to meas­ure plas­ma lev­els of vasoac­tive com­pounds through­out the year to estab­lish wheth­er or not there were any fluc­tu­a­tions which could play a part in the high­er win­ter inci­dence.
Methods. We meas­ured plas­ma lev­els of the vas­o­con­stric­tive endo­the­lin-1(ET) and the vasor­e­lax­ant ­nitric oxide (NO) through­out the year. Blood sam­ples were col­lect­ed from 176 nor­mal indi­vid­u­als. Samples were col­lect­ed ­between 8.00 and 10.00 hours after an over­night fast of at least 12 hours.
Results. Results were divid­ed into two-month­ly inter­vals and ana­lysed using a Kruskal-Wallis one-way anal­y­sis of var­i­ance and Mann-Whitney U tests (SPSS). We found a sig­nif­i­cant sea­son­al vari­a­tion in both param­e­ters. Mean lev­els of endo­the­lin were high­est in January/February (4.0 pg/ml) and low­est in May/June (2.3 pg/ml), where­as plas­ma 5 ­nitric oxide lev­els were low­est in January/February (5.7 μM) and high­est in Septem-ber/October (9.9 μM); p val­ues were <0.0001 (Jan/Feb vs May/June) and 0.049 (Jan/Feb vs Sept/Oct), respec­tive­ly.
Conclusions. The high lev­els of the vas­o­con­stric­tor endo­the­lin com­bined with low lev­els of vasor­e­lax­ant ­nitric oxide may ­account in part for the ­increased inci­dence of ­stroke and cor­o­nary heart dis­ease seen in these ­months.