236.
THE PULMONARY VASCULAR STRUCTURE OF THE PLATEAU PIKA AND RATS AT
HIGH ALTITUDE. Xiaoqin Wang
1
, Zangong Wang
1
, Qiuhong Chen
1
, Zigong Wang
1
, Jialing
Wen
1
, Akio Sakai
2
. High
1
, Shinshu University, Medical School, Matsumoto, Japan
2
.
To investigate the changes of pulmonary vasculature of plateau pika and rats living at high
altitude, 15 pikas were captured and experimented at 3780 m, 14 Wistar rats were living at 2260
m and transported to 3780 m for one month before experiment, and as a control animals.
Observation of the thickness of the small pulmonary arteries were selected diameter of
50~150_m. Microscope examination showed that Pikas have a thin-walled pulmonary arteries
with a very thin media bounded by inner and outer elastic (thickness was 14.34±0.58_m ),
whereas the rats presented a marked thick muscular pulmonary arteries (thickness was
33.12±0.92_m, (P<0.01). The percentage of the wall sickness of the small pulmonary arteries in
the pikas and rats was 12.42% and 28.40%, respectively (P<0.01). The arterioles has a wall
composed of a single elastic lamina without muscular layer. There was a positive correlation
between the thickness of the small pulmonary arteries and the mean Ppa (r=0.676, P<0.01). The
lower Ppa and the thin-walled pulmonary arteries also an adaptive mechanism to high altitude in
this mountain species.
237.
ROLE OF ENDOGENOUS NITRIC OXIDE IN HYPOXIC PULMONARY
VASOCONSTRICTION IN RATS EXPOSURE TO COLD. Kenya Watanabe
1
, Zonghai Ruan
1
,
Tomonobu Koizumi
1
, Keshi Kubo
1
, Akio Sakai
2
.
The present study was designed to see an alteration of hypoxic pulmonary vasoconstriction
(HPV) after an exposure to cold in rats. The second purpose of our study was to examine the
effects of endogenous nitric oxide synthase (NOS) inhibition on the alteration of HPV after an
exposure to cold. Systemic and pulmonary cannulations were performed to measure the pressures
in awake, unrestrained rats. Nine or ten-week old male Wistar rats were randomly assigned to the
control group (25 _) and cold exposure group (7day, 3.5 ± 1). After 7 days of cold exposure,
pulmonary artery pressure (Ppa) significantly increased, compared with the control group
(16.4±1.8 vs 10.8±1.5mmHg). Hemodynamic measurements in a plastic box corresponding to
hypoxia (12% oxygen) were performed with and without NOS inhibition, L-NAME (3 mg.kg-1),
a potent stereospecific competitive NOS inhibitor. After L-NAME administration, there were no
significant changes in Ppa in both groups at baseline. HPV response in normal rat was unchanged
with and without L-NAME. However, after hypoxic challenge, HPV response in cold group
(8.5±9.5%) was diminished compared to that in control (32.8±10.3%). The decreased HPV was
restored after L-NAME administration (from 8.5±9.5% to 33.5±14.6%). We conclude that NO
could participate in regulating the pulmonary circulation after the cold exposure and that
augmented endogenous NO production could contribute to decreased HPV after cold exposure in
rats.
238.
THE CONTRAST OBSERVATION OF INHALING LOW CONCENTRATION NITRIC
OXIDE IN TREATING HIGH ALTITUDE PULMONARY EDEMA. Wang Wei
1
. Institute of
High Altitude Medicine, PLA, China
1
.
We treated 22 patients who have high altitude pulmonary edema (HAPE) by inhaling nitric
oxide (NO) at 3700m, 19 patients by regular treatment and 24 patients by nifedipine as contrast.
In this experiment we aimed to observe the therapeutic effects of NO in the treatment of HAPE.
65 male patients with HAPE were divided into 3 groups randomly. Patients in the regular therapy
group (A group) received oxygen, intravenous furosemide, aminophylline and dexamethasone;
patients in the nifedipine group (B group) received oral nifedipine (10mg, tid) in addition to
regular therapy; and patients in the NO group (C group) inhaled NO (10ppm) for 30 min in
addition to oral nifedipine. The time for which pulmonary rales on auscultation and shadows on
chest radiograph lasted and the course of disease were compared. In C group, pulmonary rales
disappeared in 0.4±0.3d, shadows on chest radiograph disappeared in 0.6±0.2d, and the course of
