Abstract
The effects of exposing rats to hypoxia at normal atmospheric pressure for periods of 21-24 days on intrapulmonary conversion of angiotensin I (ANG I) to angiotensin II (ANG II) were examined using an isolated rat lung preparation perfused at constant flow. 125I-ANG I (160 fmol) was injected alone and with graded doses (0.1, 1.0, and 100 nmol) of unlabeled ANG I into the pulmonary artery, and the effluent was collected for measurement of ANG I, ANG II, and metabolites. At low doses of injected ANG I (125I-ANG I alone or with 0.1 to 1.0 nmol unlabeled ANG I), the percent conversion of ANG I to ANG II was 67.5 ± 2.1 (SE), 65.1 ± 2.0, and 62.5 ± 1.6 in 21-day hypoxia-exposed animals and 83.8 ± 2.7, 81.4 ± 3.9, and 79.6 ± 2.3 (P < 0.01) in control rats maintained under normoxic conditions. At the highest dose (100 nmol) of injected ANG I, percent conversion was reduced in both hypoxic and control groups to 46.8 ± 5.0 and 64.0 ± 6.0, respectively (P < 0.05). Mean transit times of labeled material through the pulmonary circulation were not significantly different in hypoxic vs. normoxic lungs at any ANG I load, suggesting that the decreased conversion seen in hypoxic lungs was not related to altered kinetics of substrate exposure. Thus chronic hypoxia is associated with significant inhibition of transpulmonary ANG I conversion that is independent of perfusate flow. We postulate that this phenomenon is due to alterations at the endothelial membrane level.
| Original language | English |
|---|---|
| Pages (from-to) | 1121-1127 |
| Number of pages | 7 |
| Journal | Journal of Applied Physiology |
| Volume | 60 |
| Issue number | 4 |
| State | Published - Jan 1 1986 |
| Externally published | Yes |
Fingerprint
ASJC Scopus subject areas
- Endocrinology
- Physiology
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation
Cite this
Impaired pulmonary conversion of angiotensin I to angiotensin II in rats exposed to chronic hypoxia. / Jackson, Robert; Narkates, A. J.; Oparil, S.
In: Journal of Applied Physiology, Vol. 60, No. 4, 01.01.1986, p. 1121-1127.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Impaired pulmonary conversion of angiotensin I to angiotensin II in rats exposed to chronic hypoxia
AU - Jackson, Robert
AU - Narkates, A. J.
AU - Oparil, S.
PY - 1986/1/1
Y1 - 1986/1/1
N2 - The effects of exposing rats to hypoxia at normal atmospheric pressure for periods of 21-24 days on intrapulmonary conversion of angiotensin I (ANG I) to angiotensin II (ANG II) were examined using an isolated rat lung preparation perfused at constant flow. 125I-ANG I (160 fmol) was injected alone and with graded doses (0.1, 1.0, and 100 nmol) of unlabeled ANG I into the pulmonary artery, and the effluent was collected for measurement of ANG I, ANG II, and metabolites. At low doses of injected ANG I (125I-ANG I alone or with 0.1 to 1.0 nmol unlabeled ANG I), the percent conversion of ANG I to ANG II was 67.5 ± 2.1 (SE), 65.1 ± 2.0, and 62.5 ± 1.6 in 21-day hypoxia-exposed animals and 83.8 ± 2.7, 81.4 ± 3.9, and 79.6 ± 2.3 (P < 0.01) in control rats maintained under normoxic conditions. At the highest dose (100 nmol) of injected ANG I, percent conversion was reduced in both hypoxic and control groups to 46.8 ± 5.0 and 64.0 ± 6.0, respectively (P < 0.05). Mean transit times of labeled material through the pulmonary circulation were not significantly different in hypoxic vs. normoxic lungs at any ANG I load, suggesting that the decreased conversion seen in hypoxic lungs was not related to altered kinetics of substrate exposure. Thus chronic hypoxia is associated with significant inhibition of transpulmonary ANG I conversion that is independent of perfusate flow. We postulate that this phenomenon is due to alterations at the endothelial membrane level.
AB - The effects of exposing rats to hypoxia at normal atmospheric pressure for periods of 21-24 days on intrapulmonary conversion of angiotensin I (ANG I) to angiotensin II (ANG II) were examined using an isolated rat lung preparation perfused at constant flow. 125I-ANG I (160 fmol) was injected alone and with graded doses (0.1, 1.0, and 100 nmol) of unlabeled ANG I into the pulmonary artery, and the effluent was collected for measurement of ANG I, ANG II, and metabolites. At low doses of injected ANG I (125I-ANG I alone or with 0.1 to 1.0 nmol unlabeled ANG I), the percent conversion of ANG I to ANG II was 67.5 ± 2.1 (SE), 65.1 ± 2.0, and 62.5 ± 1.6 in 21-day hypoxia-exposed animals and 83.8 ± 2.7, 81.4 ± 3.9, and 79.6 ± 2.3 (P < 0.01) in control rats maintained under normoxic conditions. At the highest dose (100 nmol) of injected ANG I, percent conversion was reduced in both hypoxic and control groups to 46.8 ± 5.0 and 64.0 ± 6.0, respectively (P < 0.05). Mean transit times of labeled material through the pulmonary circulation were not significantly different in hypoxic vs. normoxic lungs at any ANG I load, suggesting that the decreased conversion seen in hypoxic lungs was not related to altered kinetics of substrate exposure. Thus chronic hypoxia is associated with significant inhibition of transpulmonary ANG I conversion that is independent of perfusate flow. We postulate that this phenomenon is due to alterations at the endothelial membrane level.
UR - http://www.scopus.com/inward/record.url?scp=0022549666&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0022549666&partnerID=8YFLogxK
M3 - Article
C2 - 3009385
AN - SCOPUS:0022549666
VL - 60
SP - 1121
EP - 1127
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
SN - 8750-7587
IS - 4
ER -