LOWER LEVEL OF eNOS AND C-TYPE NATRIURETIC PEPTIDE IN PATIENTS WITH ISOLATED SYSTOLIC HYPERTENSION

Abstract

Background: Isolated systolic hypertension (ISH) is defined as systolic blood pressure (SBP) ≥140 mmHg and diastolic blood pressure (DBP) <90 mmHg. ISH occurs as a result of arterial stiffness with major health consequences if uncontrolled. Abnormal level of endothelial nitric oxide synthase (eNOS), C-type natriuretic peptide (CNP), Brain natriuretic peptide (BNP) and cyclic guanosine monophosphate (cGMP) are expected to be associated with arterial stiffness.  However, direct associations of these factors with ISH are still unclear. Changes of plasma level of these factors in ISH and hypertensive patients (both SBP and DBP are high, reflecting the level of their expression and production, therefore contributing to the pathophysiology of these diseases. Methods: Samples were collected from patients in Alnoor Specialist Hospital, Makkah, Saudi Arabia. ELISA was used to measure serum level of these parameters in three groups: (I) ISH patients (n=26); (II) hypertensive patients (n=12) and (III) normal subjects (n=12). Results: In ISH, there is decrease in serum level of eNOS (0.06±0.006; n=32) and CNP (0.08±0.01; n=26) as compared to normal subjects (p<0.05). CNP is lower in ISH as compared to hypertensive (0.16±0.03; n=12; p<0.05). No changes in NT-proBNP (0.13±0.02; n=35) as compared to normal and hypertensive groups (p>0.05). In hypertensives, low serum level of eNOS (p<0.05) were found, but not CNP (0.16±0.03; n=12) or NT-proBNP (0.13±0.02; n=15) as compared to normal subjects (p>0.05). Conclusion: Down-regulation of eNOS and CNP in ISH suggest their possible involvement in the pathophysiology of ISH. These findings open a new understanding of the pathophysiology of ISH and hypertension and bring hope for better treatment of these diseases.