Improved blood pressure, nitric oxide and asymmetric dimethylarginine are independent after bariatric surgery

Obesity is associated with hypertension, but the exact mechanism is not fully understood. Bariatric surgery significantly decreases weight and blood pressure (BP). Low plasma nitric oxide (NO) and raised asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO, concentrations are associated with both obesity and hypertension. Correlations between the changes in these parameters were studied after bariatric surgery.

Weight, BP, plasma ADMA and NO were measured in 29 obese patients (24 female, 5 male) before and six weeks after bariatric surgery.

Patients were 39.2 ± 1.2 (mean ± SEM) years old and weighed 126 ± 3 kg. Six weeks after the surgery, patients had lost 10 ± 0.7 kg (P < 0.0001) and mean arterial pressure (MAP) decreased by 11 ± 1.0 mmHg (P < 0.0001). The plasma ADMA concentration decreased by 24 ± 2% from 5 ± 0.4 to 4.0 ± 0.3 micromol/L (P < 0.0001). The plasma total nitrite concentration increased by 15 ± 1% from 51.4 ± 2.6 to 60 ± 3 micromol/L (P < 0.0001). The correlation between the decrease of ADMA and increase of NO subsequent to weight loss was significant (P < 0.0001). However, MAP was not correlated to the changes in ADMA or NO.

After bariatric surgery, beneficial changes in BP, NO and ADMA occur, but our findings suggest that these BP changes are independent of changes in the NO-ADMA axis. Other causes for the changes in BP should therefore be considered.