EFFECTS OF GLYCYRRHIZIC ACID ON RIGHT ATRIAL PRESSURE AND PULMONARY VASCULATURE IN RATS

Glycyrrhizic acid (GCA) the active component of liquorice acts by inhi biting 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD) which catal yses the reversible conversion of cortisol to cortisone. The aim of th is study was to examine the effect of GCA on pulmonary arterial pressu re. Male Sprague-Dawley rats (200 g) received drinking water containin g 0.1 mg/ml and 1.0 mg/ml GCA for 12 weeks. Tail blood pressure (BP) w as recorded every three weeks and serum Na and were measured at the be gining and the end of the experiment. Right atrial pressure (RAP) were measured at the end of 12 weeks just before the animals were sacrific ed. Lung tissues were taken for histological examination using the ela stic-van Gieson (EVG) staining method. There was a significant increas e in tail BP in GCA treated rats compared to controls, for both dosage s used. This was associated with an increase in serum Na+ and a decrea se in K+ level. The mean RAP increased significantly from 2.69 +/- 0.2 3 mmHg to 4.47 +/- 0.32 mmHg (P < 0.001) in 0.1 mg/ml GCA treated rats and 6.86 +/- 0.54 mmHg (P < 0.0001) in rats receiving 1.0 mg/ml GCA i n the water. Histological examination showed increased thickness of pu lmonary arterial wall (P < 0.0001). In conclusion GCA caused an increa se in right atrial pressure as well as thickening of the pulmonary ves sels suggesting pulmonary hypertension.