Effect of Olea europea L. leaf extract on haemodynamic status and lipid peroxidation in spontaneously hypertensive rats

Abstract

Hypertension is one of the main causes of cardiovascular disorders and since ancient times olive tree leaves have been used in its therapy. However the mechanisms of their atihypertensive effect have not been sufficiently explained yet. The main objective of our study was to investigate acute effect of olive tree leaves extract on haemodynamics and lipid peroxidation in rats with congenital hypertension under normal and blocked synthesis of nitric oxide. For the purpose of our research, there were used olive tree leaf extract EFLA® 943 as well as inhibitor of nitric oxide synthase enzyme L-NAME. Nitric oxide synthesis inhibition led to statistically significant increase of mean arterial pressure, reducing heart rate and cardiac output, increase of total vascular resistance and lipid peroxidation in plasma. Treatment by olive leaf extract led to decrease of mean arterial pressure, reducing the frequency and cardiac output, without change in lipid peroxidation. Olive leaf extract under blockade of nitric oxide led to decrease of mean arterial pressure, total peripheral resistance remained high, cardiac output low, and lipid peroxidation significantly increased. General conclusion is that olive leaf extract has a strong antihypertensive effect, decreases cardiac pre and after load and does not influence lipid peroxidation. Under blockade of nitric oxide synthesis, this extract keeps antihypertensive properties, but due to strong endothelial dysfunction, it is unable to regulate increased total peripheral resistance and marked lipid peroxidation.

Hipertenzija je jedan od vodećih uzroka nastanka kardiovaskularnih oboljenja. Listovi masline se još od davnina koriste u lečenju hipertenzije, međutim mehanizmi njihovog antihipertenzivnog delovanja još uvek nisu dovoljno razjašnjeni. Glavni cilj naše studije bio je da ispitamo akutno dejstvo ekstrakta lista masline na hemodinamiku i lipidnu peroksidaciju pacova sa urođenom hipertenzijom u uslovima normalne i blokirane sinteze azotnog monoksida. Korišćeni su ekstrakt lista masline EFLA®943 i blokator enzima azot monoksid sintaze L-NAME. Blokada sinteze azotnog monoksida je dovela do statistički značajnog povećanja srednjeg arterijskog pritiska, smanjenja frekvence i minutnog volumena srca, povećanja ukupnog perifernog otpora i povećanja lipidne peroksidacije u plazmi. Tretman ekstraktom lista masline je doveo do sniženja srednjeg arterijskog pritiska, smanjenja frekvence i minutnog volumena srca, bez promena lipidne peroksidacije. Ekstrakt lista masline u uslovima blokade azotnog monoksida je doveo do sniženja srednjeg arterijskog pritiska, ukupni periferni otpor je ostao visok, minutni volumen nizak, a lipidna peroksidacija značajno povišena. Opšti zaključak je da ekstrakt lista masline iskazuje snažno antihipertenzivno dejstvo, smanjuje volemijsko i tenziono opterećenje srčanog mišića i ne menja stepen lipidne peroksidacije. U uslovima blokirane sinteze azotnog monoksida, ovaj ekstrakt zadržava antihipertenzivno svojstvo, ali usled izazvane snažne endotelne disfunkcije ne poboljšava sistemsku hemodinamiku i povećanu lipidnu peroksidaciju.