LONG-TERM ADMINISTRATION OF L-ARGININE DID NOT INFLUENCE BLOOD-PRESSURE, HEART-RATE, CARDIAC-HYPERTROPHY OR ARTERIAL-WALL THICKNESS OF SPONTANEOUSLY HYPERTENSIVE RATS
F. Kristek, LONG-TERM ADMINISTRATION OF L-ARGININE DID NOT INFLUENCE BLOOD-PRESSURE, HEART-RATE, CARDIAC-HYPERTROPHY OR ARTERIAL-WALL THICKNESS OF SPONTANEOUSLY HYPERTENSIVE RATS, Experimental physiology, 83(5), 1998, pp. 595-603
The aim of this study was to evaluate whether long-term administration
of L-arginine, a physiological substrate for the production of nitric
oxide, improved blood pressure, heart rate, cardiac hyper trophy and
particularly structural changes in the coronary and carotid artery of
spontaneously hypertensive rats (SHR). The experiments started with th
ree groups of 10-week-old animals: control Wistar rats, untreated SHR
and SHR treated with L-arginine (SHR + L-arginine). L-Arginine was adm
inistered to SHR in a daily dose of 300 mg kg(-1) intraperitoneally fo
r 6 weeks. Blood pressure and heart rate were recorded each week. At t
he end of the experiment in one-half of each group heart weight and bo
dy weight were determined and the heart weight/body weight index was c
alculated. In the other animals, the cardiovascular system was perfuse
d via the left ventricle with a glutaraldehyde fixative at 120 mmHg an
d the coronary and carotid arteries were processed for transmission el
ectron microscopy. The inner diameter and wall thickness (tunica intim
a and tunica media) were measured on semithin sections. The reliabilit
y of the genetic feature in the SHR group was proved by the increased
heart weight, heart weight/body weight index, wall thickness and wall
thickness/inner diameter ratio of coronary and carotid arteries in com
parison to the group of control Wistar rats. Long-term administration
of L-arginine did not significantly influence blood pressure and heart
rate in comparison with untreated SHR. Neither were any differences f
ound in cardiac hypertrophy or the geometry of the coronary and caroti
d arteries (thickness of arterial wall, inner diameter, wall/diameter
ratio). In conclusion, the changes in the cardiovascular system in SHR
were not reversed, or even alleviated, by chronic treatment with L-ar
ginine.