[NOS activity in vascular smooth muscle cells of hypertension patients and the effect of AVP on NO synthesis].
OBJECTIVE
To investigate the changes of nitric oxide (NO) and nitric oxide synthase (NOS) in vascular smooth muscle cells (VSMCs) of the essential hypertension (EH) patients, determine the effect of arginine vasopressin (AVP) on NO synthesis, and evaluate their significance in the pathogenesis of hypertension.


METHODS
VSMCs of EH and normotensives (NT) were isolated by compound collagenase method and cultured in vitro. We detected the NO concentration and the activity of NOS in cell culture medium and determined the effects of AVP on NO synthesis and NOS activity.


RESULTS
NO concentration and the activity of NOS in VSMCs of EH were 0.84 nmol/2.5 x 10(6) cells +/- 0.08 nmol/2.5 x 10(6) cells and (0.23 nmol/min +/- 0.08 nmol/min per 2.5 x 10(6) cells respectively, which were significantly lower than in VSMCs of NT (2.48 nmol/2.5 x 10(6) cells +/- 0.19 nmol/2.5 x 10(6) cells, 0.37 nmol/min +/- 0.06 nmol/min per 2.5 x 10(6) cells, respectively, both P < 0.01). Under AVP induced conditions, NO concentration 3.89 +/- 0.33 nmol/2.5 x 10(6) cells and NOS activity 1.81 nmol/min 2.5 x 10(6) cells +/- 0.09 nmol/min 2.5 x 10(6) cells) in VSMCs of EH were significantly lower than in VSMCs of NT (9.09 nmol/2.5 x 10(6) +/- 0.75 nmol/2.5 x 10(6) cells), 2.80 nmol/min 2.5 x 10(6) cells +/-0.21 nmol/min 2.5 x 10(6) cells, respectively, both P < 0.01). NO concentration and NOS activity in VSMCs of both EH and NT group increased in a culture-time-dependent and AVP-concentration-dependent manner (both P < 0.01). NO concentrations in VSMCs of EH in different culture time increased with the enhancement of NOS activity, and there was significant positive relevance between them (4 h r = 0.940, P < 0.01; 8 h r = 0.993, P < 0.01.


CONCLUSIONS
NOS-NO system of EH, with attenuated responsiveness to AVP, is probably abnormal in structure or function, and is involved in the pathogenesis of essential hypertension.
Zhao
L
L
Department of Cardiology, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, China.
Li
H
H
Li
X
X
D000368:Aged; D001127:Arginine Vasopressin / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D006490:Hemostatics / Q000494:pharmacology*; D006801:Humans; D006973:Hypertension / Q000201:enzymology*; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology*; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III; D013997:Time Factors
D006490:Hemostatics; D001127:Arginine Vasopressin; D009569:Nitric Oxide; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III