Increased blood kynurenine level as a factor inhibiting the therapeutic effect of antihypertensive agents in combined long-term treatment of essential hypertension.

Results of a three-year antihypertensive combined treatment of 24 male patients with essential hypertension aged 35-55 years are presented. In all patients the blood serum kynurenine level after tryptophan load was determined before treatment and after the 1st, 2nd and 3rd years of therapy. It was found that in a part of patients the long-term administration of antihypertensive drugs led to an increased accumulation of kynurenine as a manifestation of pyridoxal-5-phosphate deficiency. The development and preservation of an increased blood kynurenine level interferes with the positive effects of antihypertensive therapy as regards both blood pressure and left ventricular myocardial mass reduction.