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Biomedical subjects

F Broughton Pipkin

Publications and source records attributed to F Broughton Pipkin.

At least 127 records · Page 7Linked to original sources
PubMed1982

Angiotensin-converting enzyme and the renin-angiotensin system in normotensive primigravid pregnancy.

In a prospective study the interactions between ACE and the renin-angiotensin system in 18 primigravid normotensive women were investigated throughout pregnancy. ACE activity was found to be depressed throughout pregnancy, rising in the last trimester and returning to non-pregnant values by 6 weeks post partum. No significant differences were found between cord arterial or venous and maternal venous ACE levels at delivery. ACE was inversely related to systolic and mean arterial blood pressures, inversely to serum sodium and urinary potassium and directly to serum potassium levels. Within the system, ACE was correlated only to aldosterone levels. In company with other components of the system ACE activity appears to be altered in pregnancy and to be influenced by similar control mechanisms. It is possible that ACE plays a modulating role on aldosterone secretion via the (des-asp1), Angiotensin I pathway.

Birth Weight↗
PubMed1981

Effects and interactions of prostaglandins E1 and E2 on human chorionic plate arteries.

Helically cut strips of human chorionic plate arteries were maintained in a physiologic salt solution in vitro while isotonic measurements of contraction were made. The arterial strips were exposed to two prostaglandins, PGE1 and PGE2, added cumulatively to the tissue baths. The effects and interactions of these two prostaglandins were examined. PGE1 had a dose-dependent relaxatory effect on the strips at low concentrations, but contracted them at higher concentrations. PGE2, on the other hand, only induced contraction. The addition of a low concentration of PGE2 inhibited the relaxatory response to PGE1 in approximately half the tissue strips. The contractile response was enhanced in all strips. Conversely, a low concentration of PGE2. The suggestion is made that, in the human term placenta, PGE1 and PGE2 may act in concert as part of the regulatory mechanism for fetoplacental.

Adolescent↗
PubMed1981

Angina-like pain: an unexpected side-effect following the simultaneous administration of angiotensin II and prostaglandin E2 in normal adults.

Two fit young, non-pregnant adults both experienced marked retrosternal chest pain and chest tightness when receiving 8 ng kg-1 min-1 AII simultaneously with 5 microgram min-1 PGE2. This dose of AII is well within that given experimentally by various workers, and was without such effect when initially given in the absence of PGE2 infusion. The combination dangerous one.

Adult↗
PubMed1981

A prospective study of plasma angiotensin-converting enzyme in normotensive primigravidae and their infants.

Plasma angiotensin-converting enzyme (ACE) has been measured prospectively throughout pregnancy, at delivery and in the puerperium in 18 normotensive primigravidae and their infants. Plasma ACE was consistently lower during pregnancy than in comparable, non-pregnant controls, but rose progressively from about 30 weeks to term. At vaginal delivery maternal and fetal ACE levels did not differ significantly. There was a steady increase in maternal ACE activity up to 6 weeks post partum, when the levels were not significantly different from non-pregnant controls. No correlation could be found between plasma ACE and plasma renin activity or concentration, or plasma AII. Plasma aldosterone increased in parallel with ACE during the last ten weeks of pregnancy.

Adult↗
PubMed1981

Renin and angiotensin levels in children.

Plasma renin activity, plasma renin concentration, and angiotensin II levels were measured in 63 normal children aged between 2 months and 12 years. The results showed that the high levels of renin and angiotensin II present in infancy remained above adult levels throughout the first decade of life but that there was a decline with age. Boys less than 8 years old had lower plasma renin activity and angiotensin II levels than girls of a similar age; this may be due to a relative substrate deficiency. Serum urea levels were inversely correlated with plasma renin activity in both sexes. A significant inverse relationship was found between both plasma renin activity and angiotensin II, and serum sodium in the girls; a similar, although not statistically significant, relationship was seen with plasma renin activity in the boys. An inverse correlation was found between plasma renin concentration and diastolic blood pressure for the group as a whole.

Aging↗
PubMed1980

Factors affecting plasma angiotensin II concentration in labour.

Concentrations of plasma angiotensin II (AII) have been measured in the second stage of labour or before delivery by elective Caesarean section in 134 women and some factors influencing the levels have been assessed. Plasma AII concentrations in the second stage of labour were higher than levels previously observed before the onset of labour in both primigravid and multiparous women. Markedly lower levels were found following delivery by elective Caesarean section than following vaginal delivery. Multiparae had higher AII concentrations than primigravidae both before the onset of labour and at delivery. Epidural analgesia was associated with significantly lower AII concentrations; in primigravidae receiving such analgesia a statistically significant relation was found between AII concentration and diastolic blood pressure at delivery. A similar relation was found in the nonproteinuric patients delivered by Caesarean section. The estimated duration of the second stage of labour was the major factor affecting AII concentration in normal multiparae. In both primigravid and multiparous women, AII concentrations were markedly raised in association with proteinuria.

Adult↗
PubMed1980

Comparison of the alpha and beta blocking drug, labetalol, and methyl dopa in the treatment of moderate and severe pregnancy-induced hypertension.

Twentysix women with pregnancy-induced hypertension have been randomly treated with either labetalol or Aldomet. A more satisfactory control of blood pressure was obtained with labetalol with minimal side-effects. After two weeks of treatment with labetalol renal function had significantly improved with a markedly lower incidence of proteinuria. More patients went into spontaneous labour following labetalol than following Aldomet; the Bishop score was also higher in this group. No adverse effects attributable to labetalol were noted in the baby either ante- or post-natally.

Adult↗
PubMed1979

Sequential changes in the human renin-angiotensin system following therapeutic termination of pregnancy.

Plasma renin and angiotensin II levels were measured in nine patients immediately before and at half-hourly intervals in the four hours following therapeutic termination of pregnancy. There was a small fall in renin and angiotensin II levels over the first 1 to 2 hours, followed by a slight increase. The magnitude of these effects was much smaller than those previously seen following normal delivery. It is concluded that in early pregnancy maternal, rather than feto-placental, factors are controlling the renin-angiotensin system.

Abortion, Therapeutic↗
PubMed1979

The effects of deprivation of prostaglandin precursors on vascular sensitivity to angiotensin II and on the kidney in the pregnant rabbit.

1 Pregnant rabbits were deprived of essential fatty acids from day ten of pregnancy, and results compared with a control group on a normal diet. 2 At term, cannulation of jugular and carotid vessels was performed under anaesthesia, to study the vascular sensitivity to angiotensin II and basal blood pressure. 3 Plasma renin levels, urinary electrolytes and protein were measured. 4 Placental and renal tissue was examined histologically. 5 Though no changes were found in tissues, blood or urine, a markedly significant increase in response to angiotensin II was found in the group deprived of essential fatty acids. This parallels the findings in vascular response in human pre-eclampsia.

Angiotensin II↗
PubMed1979

The transfer of fatty acids across the sheep placenta.

Maternal and fetal plasma concentrations of free fatty acids, triacylglycerols and phospholipids and the profile of their fatty acids were measured in three catheterized and unanaesthetized sheep. Fetal concentrations of all three lipid fractions were low and did not correlate with maternal concentrations. There were no measurable umbilical venous-arterial differences. Linoleic acid concentrations were low in both mother and fetus. The fatty acid composition of fetal adipose tissue, liver, lung and cerebellum of five animals was analysed. Again linoleic acid levels were very low, but phospholipids contained 2-8% arachidonic acid. [14C] linoleic acid and [3H] palmitic acid were infused intravenously into three ewes. Only trace amounts of labelled fatty acids were found in fetal plasma and these were confined to the free fatty acids. 14C-label was incorporated into fetal tissue lipids, but most of this probably was due to fetal lipid synthesis from [14C] acetate or other water-soluble products of maternal [14C] linoleic acid catabolism. It is concluded that only trace amounts of fatty acids cross the sheep placenta. They are derived mainly from the maternal plasma free fatty acids and might just be sufficient to be the source of the small amounts of essential fatty acids found in the lamb fetus, but are insignificant in terms of energy supply or lipid storage.

Adipose Tissue↗
PubMed1978

Pregnancy hypertension, parity, and the renin-angiotensin system.

Factors which influence levels of plasma AII in late pregnancy have been studied in 50 primigravidas and 53 multigravidas. A highly significant relationship has been shown between diastolic blood pressure and plasma AII (r = 0.4190 p less than 0.005) in primigravidas but not in multigravidas (r = 0.205; p less than 0.3). Multiple regression analysis and analysis of covariance have been applied to a series of independent variables with plasma AII as the dependent variable. The single most important variable related to AII levels in primigravidas was diastolic blood pressure whereas in multigravidas it was proteinuria. Rhesus blood group was shown to have a significant effect in both parity groups, Rh-negative primigravid women exhibiting higher values of AII.

Adult↗