- Email: [email protected]
Placental propofol transfer and fetal sedation during maternal general anaesthesia in early pregnancy
RESEARCH LETTERS
Action of fenfluramine on voltagegated K+ channels in human pulmonary-artery smooth-muscle cells Jian Wang, Magdalena Juhaszova, John V Conte Jr, Sean P Gaine, Lewis J Rubin, Jason Xiao-Jian Yuan
M
-actin
800 600
-actin
300 200
Kv1·1
B 117
Cont
52 52
Kv1·5 Kv1·1
1·8 0·6 * 0·4
0·5
Kv1·5
␣-actin
0·4 0·3 † *
0·2 0·1
Cont
Fen
mRNA concentrations of Kv1.5 and Kv1.1 (A) and protein concentration of Kv1.5 (B) in human pulmonary-artery smooth-muscle cells before and after treatment Cont=before treatment. M=molecular weight maker; *p<0·001, p<0·05 vs Cont.
290
The work was supported by the PPH Cure Foundation and the National Institutes of Health (HL-54043 and HL-02659). JX-JY is an Established Investigator of the American Heart Foundation. 1
2
3
4
5
Abenheim L, Moride Y, Brenot F, et al. Appetite-suppressant drugs and the risk of primary pulmonary hypertension. N Engl J Med 1996; 335: 509–16. Brenot F, Herve P, Petitpretz P, Parent F, Duroux P, Simonneau G. Primary pulmonary hypertension and fenfluramine use. Br Heart J 1993; 70: 537–41. Evans AM, Osipenko ON, Gurney AM. Properties of a novel K+ current that is active at resting potential in rabbit pulmonary artery smooth muscle cells. J Physiol 1996; 496: 407–20. Yuan X-J, Wang J, Juhaszova M, Gaine SP, Rubin LJ. Attenuated K+ channel gene transcription in primary pulmonary hypertension. Lancet 1998; 351: 726–27. Weir EK, Reeve HL, Huang JMC, Michelakis E, Nelson DP, Archer SL. Anorexic agents aminorex, fenfluramine, and dexfenfluramine inhibit potassium current in rat pulmonary vascular smooth muscle and cause pulmonary vasoconstriction. Circulation 1996; 94: 2216–20.
Division of Pulmonary and Critical Care Medicine (JX-J Yuan), and Departments of Medicine, Physiology, and Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA (email: [email protected])
Placental propofol transfer and fetal sedation during maternal general anaesthesia in early pregnancy Eric Jauniaux, Beatrice Gulbis, Claire Shannon, Viviane Maes, Lesley Bromley, Charles Rodeck
Fen
89 kDa
1·0
mRNA (arbitrary unit)
Kv1·5
Kv1·5 protein (arbitrary unit)
bp 800 600 400 300 200
Fen
A
Cont
Use of the appetite suppressant fenfluramine is associated with an increased risk of primary pulmonary hypertension (PPH),1,2 which is characterised by raised pulmonary-artery pressure and vascular resistance. In pulmonary-artery smooth-muscle cells, the potassium currents through voltage-gated potassium channel (Kv) are important determinants of membrane potential, intracellular free calcium (Ca2+) concentration, and pulmonary vascular tone.3 We have shown the whole-cell Kv currents and Kv channel mRNA expression are substantially decreased in pulmonary-artery smooth-muscle cells from patients with PPH compared with the cells from patients with secondary pulmonary hypertension.4 The results suggested that the decreased mRNA expression of the Kv channel ␣ subunit, Kv1.5, is an intrinsic feature of pulmonary-artery smoothmuscle cells in these patients. In animal experiments, fenfluramine (and other appetite suppressants) increases pulmonary-artery pressure, which is believed to be caused by inhibition of potassium-channel activity and membrane depolarisation.5 Native Kv channels are heteromultimers composed of pore-forming ␣ subunits and regulatory  subunits. Kv1.5 is a Kv channel ␣ subunit gene which encodes a noninactivating or slowly-inactivating delayed rectify Kv channel in vascular smooth muscle cells. Kv1.1 is a Kv channel  subunit gene that encodes a 45 kDa protein that binds to Kv1.5 through N-terminal regions. Association of Kv ␣ and  subunits decreased the amplitude and accelerates the inactivation of the Kv currents. Treatment with fenfluramine 200 µmol/L for 60–72 h of pulmonary-
artery smooth-muscle cells from normotensive patients decreased mRNA of Kv1.5 concentrations by 50% (SD 32, n=4) but not the mRNA concentrations of Kv1.1 (n=4) and -actin (used as invariant control, figure). Consistently, the western blot analysis showed that fenfluramine also attenuated Kv1.5 protein level by 50% (7% n=4) but had no effect on ␣-actin (figure). Inhibition of gene expression of Kv1.5 decreases the number of functional Kv channels available to stabilise membrane potential. The subsequent membrane depolarisation and increase in cytosolic Ca2+ concentration cause pulmonary vasoconstriction and smooth-muscle-cell proliferation that leads to vascular remodelling. The data from this study suggest that inhibited gene transcription and expression of Kv channel ␣ subunit may play an important role in fenfluramine-induced chronic pulmonary hypertension.
Propofol is a short-acting intravenous general anaesthetic agent with a rapid onset of action which is used in various surgical procedures and, in particular, in surgical termination of pregnancy before 24 weeks of gestation. Maternal and fetal propofol concentrations1,2 and, more recently, amniotic fluid concentrations3 have been reported in pregnancies at term but there is no information on placental transfer of this drug during the first or second trimesters of pregnancy. Samples of maternal blood, coelomic fluid, and amniotic fluid were obtained from 30 women with apparently normal pregnancies requesting termination for psychosocial reasons under general anaesthesia at 7–11 weeks of gestation. The samples were retrieved by transvaginal puncture under ultrasonographic guidance. Coelomic fluid was first aspirated and within 10 s, amniotic fluid was aspirated with another needle. In a further series of 14 women, samples of maternal and fetal blood and amniotic fluid from pregnancies at 12–18 weeks’ gestation were also obtained as described above.
THE LANCET • Vol 352 • July 25, 1998
RESEARCH LETTERS
anaesthesia, the fluid cavities surrounding the developing embryo do not act as a reservoir for this drug.
4
This work was supported by a grant of the David and Alice Van Buuren Foundation (Université Libre de Bruxelles, Bruxelles, Belgium).
MS
3
1
2 2
FS
1
3
4
0
2
6
8
10 12 14 Time (min)
16
18
20
18
20
2 1·5 1 0·5 0 4
6
8 10 12 Time (min)
14
16
Individual measurements of propofol concentration in maternal serum (MS) and fetal serum (FS) and ratio of fetal and maternal serum concentrations
Fetal blood was obtained by transabdominal cardiac puncture. In each case, a detailed transvaginal ultrasound was done to confirm gestational age and to assess spontaneous and reflex fetal movements. Written consent was obtained from each woman after receiving complete information on the procedure. This study was approved by the University College London Hospitals Committee on the Ethics of Human Research. The fetal samples were collected between 5 and 20 min following intravenous (IV) administration of a bolus of 3 mg/kg of propofol (Diprivan 1%, Zeneca, Macclesfield, UK) to the mother. Peripheral maternal venous blood was collected simultaneously. Anaesthesia was maintained by spontaneous breathing of 70% nitrous oxide with 0·5–1% isoflurane in oxygen via a laryngeal mask. The propofol concentration was determined by high-performance liquid chromatography with fluorescence. The method has a lower limit of sensitivity of 0·1 g/mL and the intra-assay and interassay coefficients of variation were both 5%. No spontaneous fetal movements or reflux responses were observed in any case during the time interval between induction of anaesthesia and the surgical procedure or during the sampling procedure. Propofol was detected in all maternal and fetal serum samples. No propofol was found in coelomic or amniotic fluid samples at any stage of gestation. Propofol concentration decreased exponentially with time in both maternal (r=⫺0·73, p<0·0001) and fetal (r=⫺0·58, p<0·0001) serum. Maternal serum concentration of propofol was always higher than fetal serum concentration. In 14 matched samples, the mean propofol concentration was 1·96 g/mL (95% CI 1·49–2·42) in maternal serum and 0·90 g/mL (95% CI 0·68–1·11) in fetal serum. Over the 20 min interval between injection and sampling, little change was observed in the fetal/maternal propofol concentration ratio. This finding can be explained by the fact that propofol binds 97–98% to albumin, which is in much lower concentration in fetal serum during the first half of pregnancy. Overall, the pharmacodynamics of propofol found in pregnant women at 12–18 weeks of gestation are similar to those described at term1–3 indicating that our data can be extrapolated to the period of gestation between 24 and 37 weeks and that our model can be used to study the placental transfer of other analgesic drugs in early pregnancy. Propofol has no known teratogenic effect in humans and our results also indicate that, during short maternal general
THE LANCET • Vol 352 • July 25, 1998
Academic Departments of Obstetrics and Gynaecology (E Jauniaux), and Anaesthetics, University College London, London WC1E 6HX, UK; Department of Clinical Chemistry, Academic Hospital Erasme, Université Libre de Bruxelles; and Department of Clinical Chemistry, Academisch Ziekenhuis, Vrije Universiteit Brussel, Belgium
Riboflavin to treat nucleoside analogue-induced lactic acidosis Brian Fouty, Frank Frerman, Randall Reves
Patients with AIDS have developed lactic acidosis and hepatic steatosis while taking nucleoside reversetranscriptase inhibitors (NRTI) such as zidovudine 1 and didanosine.2 NRTIs inhibit DNA polymerase ␥, responsible for mitochondrial DNA synthesis. Inhibition of mitochondrial DNA synthesis has been proposed as the mechanism responsible for lactic acidosis and hepatic steatosis. We considered that there must be other factors involved because, despite the predictable effects of these agents on DNA polymerase ␥, lactic acidosis is uncommon, and because we and others 1,2 have observed that lactic acidosis is not readily reversible after discontinuation of NRTI. The electron-transport chain requires a number of cofactors for proper function, in particular the flavoprotein co-factors, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). 3 Riboflavin is the precursor of FMN and FAD. Mild to moderate riboflavin deficiency is common in HIV-1-infected individuals, 4 and the enzyme which transforms riboflavin into FMN and FAD, A 400 Urine lactate (mmol/L)
2
Riboflavin (50mg)
300 200
4h
100 0 -16 10
Urine lactate (mmol/L)
FS/MS
0
Kanto J, Rosenberg P. Propofol in caesarean section: a pharmacokinetic and pharmacodynamic study. Methods Find Exp Clin Pharmacol 1990; 12: 707–11. Gin T, Yau G, Chan K, et al. Disposition of propofol infusions for caesarean section. Can J Anaesth 1991; 38: 31–36. Ragno G, Cicinelli E, Schonauer S, et al. Propofol assay in biological fluids in pregnant women. J Pharm Biomed Anal 1997; 15: 1633–40.
8
-11
-6
-1
4
9
14
19
B
10 Serum lactate BUN
8
6
6
4
4
2
2
0 -16 -12 -8
BUN (mg/dL)
Propofol (g/mL)
5
0 -4
0
4 8 Days
12 16 20 42
Changes in urine lactate, serum lactate, and BUN after riboflavin Urine flow and renal function were constant during this time.
291
Action of fenfluramine on voltagegated K+ channels in human pulmonary-artery smooth-muscle cells Jian Wang, Magdalena Juhaszova, John V Conte Jr, Sean P Gaine, Lewis J Rubin, Jason Xiao-Jian Yuan
M
-actin
800 600
-actin
300 200
Kv1·1
B 117
Cont
52 52
Kv1·5 Kv1·1
1·8 0·6 * 0·4
0·5
Kv1·5
␣-actin
0·4 0·3 † *
0·2 0·1
Cont
Fen
mRNA concentrations of Kv1.5 and Kv1.1 (A) and protein concentration of Kv1.5 (B) in human pulmonary-artery smooth-muscle cells before and after treatment Cont=before treatment. M=molecular weight maker; *p<0·001, p<0·05 vs Cont.
290
The work was supported by the PPH Cure Foundation and the National Institutes of Health (HL-54043 and HL-02659). JX-JY is an Established Investigator of the American Heart Foundation. 1
2
3
4
5
Abenheim L, Moride Y, Brenot F, et al. Appetite-suppressant drugs and the risk of primary pulmonary hypertension. N Engl J Med 1996; 335: 509–16. Brenot F, Herve P, Petitpretz P, Parent F, Duroux P, Simonneau G. Primary pulmonary hypertension and fenfluramine use. Br Heart J 1993; 70: 537–41. Evans AM, Osipenko ON, Gurney AM. Properties of a novel K+ current that is active at resting potential in rabbit pulmonary artery smooth muscle cells. J Physiol 1996; 496: 407–20. Yuan X-J, Wang J, Juhaszova M, Gaine SP, Rubin LJ. Attenuated K+ channel gene transcription in primary pulmonary hypertension. Lancet 1998; 351: 726–27. Weir EK, Reeve HL, Huang JMC, Michelakis E, Nelson DP, Archer SL. Anorexic agents aminorex, fenfluramine, and dexfenfluramine inhibit potassium current in rat pulmonary vascular smooth muscle and cause pulmonary vasoconstriction. Circulation 1996; 94: 2216–20.
Division of Pulmonary and Critical Care Medicine (JX-J Yuan), and Departments of Medicine, Physiology, and Surgery, University of Maryland School of Medicine, Baltimore, MD 21201, USA (email: [email protected])
Placental propofol transfer and fetal sedation during maternal general anaesthesia in early pregnancy Eric Jauniaux, Beatrice Gulbis, Claire Shannon, Viviane Maes, Lesley Bromley, Charles Rodeck
Fen
89 kDa
1·0
mRNA (arbitrary unit)
Kv1·5
Kv1·5 protein (arbitrary unit)
bp 800 600 400 300 200
Fen
A
Cont
Use of the appetite suppressant fenfluramine is associated with an increased risk of primary pulmonary hypertension (PPH),1,2 which is characterised by raised pulmonary-artery pressure and vascular resistance. In pulmonary-artery smooth-muscle cells, the potassium currents through voltage-gated potassium channel (Kv) are important determinants of membrane potential, intracellular free calcium (Ca2+) concentration, and pulmonary vascular tone.3 We have shown the whole-cell Kv currents and Kv channel mRNA expression are substantially decreased in pulmonary-artery smooth-muscle cells from patients with PPH compared with the cells from patients with secondary pulmonary hypertension.4 The results suggested that the decreased mRNA expression of the Kv channel ␣ subunit, Kv1.5, is an intrinsic feature of pulmonary-artery smoothmuscle cells in these patients. In animal experiments, fenfluramine (and other appetite suppressants) increases pulmonary-artery pressure, which is believed to be caused by inhibition of potassium-channel activity and membrane depolarisation.5 Native Kv channels are heteromultimers composed of pore-forming ␣ subunits and regulatory  subunits. Kv1.5 is a Kv channel ␣ subunit gene which encodes a noninactivating or slowly-inactivating delayed rectify Kv channel in vascular smooth muscle cells. Kv1.1 is a Kv channel  subunit gene that encodes a 45 kDa protein that binds to Kv1.5 through N-terminal regions. Association of Kv ␣ and  subunits decreased the amplitude and accelerates the inactivation of the Kv currents. Treatment with fenfluramine 200 µmol/L for 60–72 h of pulmonary-
artery smooth-muscle cells from normotensive patients decreased mRNA of Kv1.5 concentrations by 50% (SD 32, n=4) but not the mRNA concentrations of Kv1.1 (n=4) and -actin (used as invariant control, figure). Consistently, the western blot analysis showed that fenfluramine also attenuated Kv1.5 protein level by 50% (7% n=4) but had no effect on ␣-actin (figure). Inhibition of gene expression of Kv1.5 decreases the number of functional Kv channels available to stabilise membrane potential. The subsequent membrane depolarisation and increase in cytosolic Ca2+ concentration cause pulmonary vasoconstriction and smooth-muscle-cell proliferation that leads to vascular remodelling. The data from this study suggest that inhibited gene transcription and expression of Kv channel ␣ subunit may play an important role in fenfluramine-induced chronic pulmonary hypertension.
Propofol is a short-acting intravenous general anaesthetic agent with a rapid onset of action which is used in various surgical procedures and, in particular, in surgical termination of pregnancy before 24 weeks of gestation. Maternal and fetal propofol concentrations1,2 and, more recently, amniotic fluid concentrations3 have been reported in pregnancies at term but there is no information on placental transfer of this drug during the first or second trimesters of pregnancy. Samples of maternal blood, coelomic fluid, and amniotic fluid were obtained from 30 women with apparently normal pregnancies requesting termination for psychosocial reasons under general anaesthesia at 7–11 weeks of gestation. The samples were retrieved by transvaginal puncture under ultrasonographic guidance. Coelomic fluid was first aspirated and within 10 s, amniotic fluid was aspirated with another needle. In a further series of 14 women, samples of maternal and fetal blood and amniotic fluid from pregnancies at 12–18 weeks’ gestation were also obtained as described above.
THE LANCET • Vol 352 • July 25, 1998
RESEARCH LETTERS
anaesthesia, the fluid cavities surrounding the developing embryo do not act as a reservoir for this drug.
4
This work was supported by a grant of the David and Alice Van Buuren Foundation (Université Libre de Bruxelles, Bruxelles, Belgium).
MS
3
1
2 2
FS
1
3
4
0
2
6
8
10 12 14 Time (min)
16
18
20
18
20
2 1·5 1 0·5 0 4
6
8 10 12 Time (min)
14
16
Individual measurements of propofol concentration in maternal serum (MS) and fetal serum (FS) and ratio of fetal and maternal serum concentrations
Fetal blood was obtained by transabdominal cardiac puncture. In each case, a detailed transvaginal ultrasound was done to confirm gestational age and to assess spontaneous and reflex fetal movements. Written consent was obtained from each woman after receiving complete information on the procedure. This study was approved by the University College London Hospitals Committee on the Ethics of Human Research. The fetal samples were collected between 5 and 20 min following intravenous (IV) administration of a bolus of 3 mg/kg of propofol (Diprivan 1%, Zeneca, Macclesfield, UK) to the mother. Peripheral maternal venous blood was collected simultaneously. Anaesthesia was maintained by spontaneous breathing of 70% nitrous oxide with 0·5–1% isoflurane in oxygen via a laryngeal mask. The propofol concentration was determined by high-performance liquid chromatography with fluorescence. The method has a lower limit of sensitivity of 0·1 g/mL and the intra-assay and interassay coefficients of variation were both 5%. No spontaneous fetal movements or reflux responses were observed in any case during the time interval between induction of anaesthesia and the surgical procedure or during the sampling procedure. Propofol was detected in all maternal and fetal serum samples. No propofol was found in coelomic or amniotic fluid samples at any stage of gestation. Propofol concentration decreased exponentially with time in both maternal (r=⫺0·73, p<0·0001) and fetal (r=⫺0·58, p<0·0001) serum. Maternal serum concentration of propofol was always higher than fetal serum concentration. In 14 matched samples, the mean propofol concentration was 1·96 g/mL (95% CI 1·49–2·42) in maternal serum and 0·90 g/mL (95% CI 0·68–1·11) in fetal serum. Over the 20 min interval between injection and sampling, little change was observed in the fetal/maternal propofol concentration ratio. This finding can be explained by the fact that propofol binds 97–98% to albumin, which is in much lower concentration in fetal serum during the first half of pregnancy. Overall, the pharmacodynamics of propofol found in pregnant women at 12–18 weeks of gestation are similar to those described at term1–3 indicating that our data can be extrapolated to the period of gestation between 24 and 37 weeks and that our model can be used to study the placental transfer of other analgesic drugs in early pregnancy. Propofol has no known teratogenic effect in humans and our results also indicate that, during short maternal general
THE LANCET • Vol 352 • July 25, 1998
Academic Departments of Obstetrics and Gynaecology (E Jauniaux), and Anaesthetics, University College London, London WC1E 6HX, UK; Department of Clinical Chemistry, Academic Hospital Erasme, Université Libre de Bruxelles; and Department of Clinical Chemistry, Academisch Ziekenhuis, Vrije Universiteit Brussel, Belgium
Riboflavin to treat nucleoside analogue-induced lactic acidosis Brian Fouty, Frank Frerman, Randall Reves
Patients with AIDS have developed lactic acidosis and hepatic steatosis while taking nucleoside reversetranscriptase inhibitors (NRTI) such as zidovudine 1 and didanosine.2 NRTIs inhibit DNA polymerase ␥, responsible for mitochondrial DNA synthesis. Inhibition of mitochondrial DNA synthesis has been proposed as the mechanism responsible for lactic acidosis and hepatic steatosis. We considered that there must be other factors involved because, despite the predictable effects of these agents on DNA polymerase ␥, lactic acidosis is uncommon, and because we and others 1,2 have observed that lactic acidosis is not readily reversible after discontinuation of NRTI. The electron-transport chain requires a number of cofactors for proper function, in particular the flavoprotein co-factors, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD). 3 Riboflavin is the precursor of FMN and FAD. Mild to moderate riboflavin deficiency is common in HIV-1-infected individuals, 4 and the enzyme which transforms riboflavin into FMN and FAD, A 400 Urine lactate (mmol/L)
2
Riboflavin (50mg)
300 200
4h
100 0 -16 10
Urine lactate (mmol/L)
FS/MS
0
Kanto J, Rosenberg P. Propofol in caesarean section: a pharmacokinetic and pharmacodynamic study. Methods Find Exp Clin Pharmacol 1990; 12: 707–11. Gin T, Yau G, Chan K, et al. Disposition of propofol infusions for caesarean section. Can J Anaesth 1991; 38: 31–36. Ragno G, Cicinelli E, Schonauer S, et al. Propofol assay in biological fluids in pregnant women. J Pharm Biomed Anal 1997; 15: 1633–40.
8
-11
-6
-1
4
9
14
19
B
10 Serum lactate BUN
8
6
6
4
4
2
2
0 -16 -12 -8
BUN (mg/dL)
Propofol (g/mL)
5
0 -4
0
4 8 Days
12 16 20 42
Changes in urine lactate, serum lactate, and BUN after riboflavin Urine flow and renal function were constant during this time.
291