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CHANGING BASAL AND STIMULATED ACTIVITY OF THE RENIN‐ANGIOTENSIN SYSTEM DURING THE SECOND HALF OF GESTATION IN THE ANAESTHETIZED PIGLET
Author(s) -
Pipkin Fiona Broughton,
Colenbrander Ben,
MacDonald Alastair A.
Publication year - 1986
Publication title -
quarterly journal of experimental physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0144-8757
DOI - 10.1113/expphysiol.1986.sp002984
Subject(s) - renin–angiotensin system , gestation , basal (medicine) , medicine , endocrinology , pregnancy , biology , blood pressure , insulin , genetics
Concentrations of components of the renin‐angiotensin system were studied in eighty anaesthetized pig fetuses aged between 57 and 112 d of gestation (term = 114±1 d). Plasma renin concentration rose from a mean value of 3·2±0·4 ng.ml −1 .h −1 (mean ± S.E.M.) at 57 d to 17·5±2·7 ng.ml −1 . h −1 at 93 d of gestation and thereafter declined to 5·0±1·6 ng. ml −1 . h −1 just prior to term. There was no distinct pattern of change in plasma renin substrate concentrations during gestation; the concentration near term (0·33±0·10 µg.ml −1 ) was not different from that at 57 d (0·50±0·18 µg.ml −1 ) or that at 93d (0·31±0·08 µg.ml −1 ) of gestation. Plasma angiotensin II concentrations increased from 33 (log 10 (mean ± S.E.M.) = 1·554±0·050) pg.ml −1 at 60 d to 232 (2·365±0·225) pg.ml −1 at 105 d of gestation, after which it decreased to 50 (1·699±0·100) pg.ml −1 in 20‐d‐old neonatal piglets. Haemorrhage of 10‐20% estimated blood volume produced no consistent changes in plasma renin substrate concentrations, and inconsistent changes in renin and angiotensin II concentrations at 85‐90 d of gestation, but a consistent increase in both renin and angiotensin II concentrations thereafter. These results indicate that the components of the renin‐angiotensin system are present in the circulation of the pig fetus, and that their responses to stimuli develop during the second half of gestation.