The morning rise of systolic blood pressure (by 24-hour ambulatory monitoring) and platelet aggregability in essential hypertension patients

Aim. To investigate the relationship between platelet aggregability (PA) and parameters of blood pressure (BP) in patients,vith essential hypertension (EH). Materials and methods. We analyzed 24-h BP recordings (SL-90207, 15-min day and 30 min night lime intervals) of 47 hospitalized males with mild to moderate EH (mean age 48+/-1 years) to assess the following parameters: mean 24-h, awake (Aw) and nighttime (N) systolic (S) and diastolic (D) BP. We assessed the morning rise (MR) of BP using the new index: a relative morning rise of systolic BP-RMRSBP - (max value of SBP from 6 am to 12 am/mean asleep SBP) x 100%. The kinetics of mean aggregate size (MAS) changes was studied with aggregation analyzer model (230LA Biola Ltd., Russia). The following parameters were used for estimation of platelet aggregability: a relative increase in MAS 2 min after beginning of sample stirring - for spontaneous aggregation (SPA) and the maximum increase in the light transmission for 0.5 microM ADP-induced aggregation (ADPI-PA). The patients were divided into two groups according to the median value of RMRSBP: group 1 (n=25, RMRSBP<121%) and group 2 (n=22, RMRSBP>121%). The differences in estimated parameters were tested by Student two tailed t-tests and presented by M+/-SE. P<0.05 was considered statistically significant. Results. No significant differences have been found between the groups by mean age, body mass index, duration of arterial hypertension, mean 24-h, awake DBP and SEP. Statistically significant differences have been found between groups by SPA, ADPI-PA, night SBP, night DBP, RMRSBP, RMRDBP. In group 2 there was a correlation between RMRSBP and SPA, but nor in group 1. Conclusions. The morning rise of systolic BP is associated with an increase of ADP-induced and spontaneous platelet aggregability in the patients with mild to moderate essential hypertension and apparently that association is more pronounced at high values of morning BP (more than 20% from mean nocturnal values of SBP).