SILDENAFIL IN PULMONARY HYPERTENSION TREATMENT: Effects in a chronic hypoxic newborn sheep. Emilio Herrera V. DMV, PhD

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HAPPOM - ALFA June 26, 2007 SILDENAFIL IN

1 HAPPOM - ALFA June 26, 2007 SILDENAFIL IN PULMONARY HYPERTENSION TREATMENT: Effects in a chronic hypoxic newborn sheep. Emilio Herrera V. DMV, PhD Laboratorio de Fisiología y Fisiopatología del Desarrollo Programa de Fisiopatología, ICBM, Facultad de Medicina, UNIVERSIDAD DE CHILE.

2 INTRODUCTION PO 2 vs Altitude Peñaloza & Arias-Stella, Beall,

3 INTRODUCTION PAP vs Altitude Monge & León-Velarde, 2004 Putre Moore y cols, 1998 Peñaloza & Arias-Stella, 2007

4 TRANSITION OF THE PULMONARY CIRCULATION Pulmonary circulation FETUS NEWBORN INTRODUCTION Resistance HIGH LOW Blood flow (ml.min -1.kg -1 ) Mechanisms Physical: air-liquid interphase, oxigen tension, shear stress. Vasoactives products: synthesis of vasodilators. Structural reorganization: endothelial, SMC & matrix.

5 INTRODUCTION TRANSITION OF THE PULMONARY CIRCULATION Steinhorn & Farrow, 2007

6 INTRODUCTION PULMONARY HYPERTENSION co co PDE5 PDE5 Modified from Strange et al, 2002

7 HYPOTHESIS HYPOTHESIS Chronic fetal hypoxia determines pulmonary vascular hyperreactivity during neonatal period. This is associated with a pulmonary hypertension, a higher expression/activity of PDE5 and a vascular remodeling.

8 HYPOTHESIS PUTRE, m CHRONIC FETAL HYPOXIA SANTIAGO, 580 m FETAL NORMOXIA HLNB LLNB NOS sgc NO Balance VC > VD PDE5 Muscularization NOS sgc NO Balance VC ~ VD PDE5

9 MATERIAL & METHODS! IN VIVO experiments - ANIMALS - CHRONIC INSTRUMENTATION - ACUTE HYPOXIA - 1h NORMOXIA - 1h HYPOXIA - 1h RECOVERY - CARDIOVASCULAR VARIABLES PAP, PcP, CO, SAP, HR. - BLOCKADE Sildenafil (16.6 ug.kg -1.min -1 )

10 MATERIAL & METHODS PHARMACOLOGICAL BLOCKADE " NOS x SILDENAFIL Modified from Strange et al, 2002

11 RESULTS Table. ph and arterial blood gases in lowland (LLNB) and highland (HLNB) newborn sheep. BASAL HYPOXEMIA RECOVERY ph LLNB RNTB HLNB RNTA a PCO 2 LLNB RNTB * mmhg HLNB RNTA a PO 2 LLNB RNTB b mmhg HLNB RNTA a b a Hb LLNB RNTB g/dl HLNB RNTA sathb LLNB RNTB b % HLNB RNTA a b a p<0.05, a vs LLNB, b vs Basal, * vs all.

12 RESULTS LOWLAND AND HIGHLAND NEWBORN LAMBS PULMONARY CIRCULATION DURING HYPOXIA + SILDENAFIL LLNB HLNB PAP (mmhg) PAP (mmhg) infusion 40 HYPOXIA Time (min) PVR (mmhg.ml -1.min.kg) PVR (mmhg.ml -1.min.kg) 0,10 0,05 0,00 0,10 0,05 0,00 bc B B+i H+i R Period * bc * bc c NaCl 0.9% Sildenafil p<0.05, b vs Basal, c vs NaCl 0.9%, * vs all.

13 RESULTS LOWLAND AND HIGHLAND NEWBORN LAMBS SYSTEMIC CIRCULATION DURING HYPOXIA + SILDENAFIL LLNB SAP (mmhg) infusion HYPOXIA SVR (mmhg.ml -1.min.kg) 0,40 0,30 0,20 0,10 0,00 c * bc NaCl 0.9% Sildenafil HLNB SAP (mmhg) Time (min) SVR (mmhg.ml -1.min.kg) 0,40 0,30 0,20 0,10 0,00 B B+i H+i R Period b p<0.05, b vs Basal, c vs NaCl 0.9%, * vs all.

14 RESULTS LOWLAND AND HIGHLAND NEWBORN LAMBS SYSTEMIC CIRCULATION DURING HYPOXIA + SILDENAFIL 400 infusion HYPOXIA 500 * Sildenafil NaCl 0.9% LLNB HR (min -1 ) CO (ml.min -1.kg -1 ) * HLNB HR (min -1 ) Time (min) CO (ml.min -1.kg -1 ) B B+i H+i R Period * * p<0.05, b vs Basal, c vs NaCl 0.9%, * vs all.

15 RESULTS SUMMARY I HIGHLAND NEWBORN PRESENTS HIGHER PULMONARY PRESSURE AND RESISTANCE. SILDENAFIL INDUCES IMPORTANT PULMONARY DILATION AND BRIEF SYSTEMIC EFFECTS. A HIGHER PDE5 FUNCTION DURING HYPOXIA. PULMONARY ARTERIES CONTRACTILITY?

150-400 um - Wire myograph Optimal diameter

(KCl,, 4,75-125 mm K + ) - Pharmacologic

16 MATERIAL & METHODS! EX VIVO experiments - Pulmonary arteries um - Wire myograph Optimal diameter (KCl,, 65 mm K + ) Maximal contraction (KCl,, 4, mm K + ) - Pharmacologic response to: SNP (10( M) ODQ (10( 10-5 M) Sildenafil (10( M)

17 RESULTS LOWLAND AND HIGHLAND NEWBORN LAMBS SMALL PULMONARY ARTERIES KCl Response LLNB HLNB 3,0 a Tension, N/m pec 50 N/m 2,0 1,0 0, KCl, mm 0 LLNB HLNB p<0.05, a vs LLNB.

18 RESULTS LOWLAND AND HIGHLAND NEWBORN LAMBS SMALL PULMONARY ARTERIES SNP Response 125 Tension, %K LLNB HLNB % dilation pd a 7.5 a Log [SNP] 0.0 LLNB HLNB p<0.05, a vs LLNB.

19 RESULTS LOWLAND AND HIGHLAND NEWBORN LAMBS SMALL PULMONARY ARTERIES SNP & ODQ Response 125 LLNB HLNB Tension, %K SNP in presence of ODQ 10-5 M Log [SNP]

20 RESULTS LOWLAND AND HIGHLAND NEWBORN LAMBS SMALL PULMONARY ARTERIES Sildenafil Response 1.25 a Relaxation (N/m) LLNB HLNB pd 2 Rmax (N/m) Log Sildenafil LLNB HLNB p<0.05, a vs LLNB.

21 RESULTS SUMMARY II HIGHLAND NEWBORN LAMB PRESENTS: A HIGHER MAXIMAL CONTRACTION. A HIGHER SENSITIVITY TO SNP. NO VASODILATES PRIMARILY BY cgmp PATHWAY. A HIGHER RELAXATION IN RESPONSE TO SILDENAFIL. PULMONARY ARTERIES REMODELING?

22 MATERIAL & METHODS! HISTOLOGICAL Experiments - Pulmonary tissue - Staining H-E van Gieson Lung PA - Analysis % Area media (Total area-luminal area).

23 RESULTS LOWLAND AND HIGHLAND NEWBORN LAMBS DISTAL PULMONARY ARTERIES Remodeling in subpleural (SP) pulmonary arteries LLNB SP Area media HLNB 100μm SP LLNB HLNB 100μm

24 RESULTS SUMMARY IV HIGHLAND NEWBORN LAMB PRESENTS: No histological differences in conduction pulmonary arteries. Smooth muscle hyperplasia in resistance pulmonary arteries (subpleura).

25 CONCLUSIONS CONCLUSIONS PULMONARY CIRCULATION IN HIGHLAND NEWBORN - PAP Y PVR - PDE5 FUNCTION - Vasodilation via cgmp - Vascular Remodeling sildenafil PARCIAL REVERTION OF THE HYPOXIC PULMONARY VASOCONSTRICTION Good therapeutic for PHPT if there is NO or few remodeling. Other pharmacological associations?

26 INCAS

27 ALFA Acknowledgements RESULTS Meeting presentations: Herrera et al. Sildenafil reverses the pulmonary hypertension in highland newborn sheep. XII Congreso Latinoamericano y 1ro Iberoamericano de Ciencias Fisiológicas. Argentina, Buenos Aires. November, Physiol Mini Rev 2 (4): 177, Ebensperger et al. The fetal chronic hypoxia during partial gestation at highlands modifies the cardiovascular response to acute hypoxia in fetal sheep. XII Congreso Latinoamericano y 1ro Iberoamericano de Ciencias Fisiológicas. Argentina, Buenos Aires. November, Physiol Mini Rev 2 (4): 176, Krause et al. Pharmacological characterization of α1-adrenergic receptors expressed in femoral arteries from high altitude newborn sheep. XII Congreso Latinoamericano y 1ro Iberoamericano de Ciencias Fisiológicas. Argentina, Buenos Aires. November, Physiol Mini Rev 2 (4): 177, Herrera et al. Cardiovascular function during basal and hypoxic conditions in highland and lowland fetal sheep. 33rd Annual Meeting of the Fetal and Neonatal Physiology Society. UK, University of Cambridge. September, Herrera et al. Increased Pulmonary sensivity to oxigen in high altitude newborn sheep. XXI Annual meeting Sociedad Chilena de Ciencias Fisiológicas. Antofagasta, Chile. August, Ebensperger et al. Lung expressión of hypoxia inducible fectors (HIF) and prolyl hydroxylases (PHD): Comparison between fetus and newborn sheep exposed to chronic hypoxia. XXI Annual meeting Sociedad Chilena de Ciencias Fisiológicas. Antofagasta, Chile. August, Papers: Herrera et al. High altitude chronic hypoxia during gestation and after birth modifies cardiovascular responses in newborn sheep. Am J Physiol Regul Integr Comp Physiol. 292(6):R , Herrera et al. Sildenafil reverses hypoxic pulmonary hypertension in highland and lowland newborn sheep. In revision Pediatr Res, jun 2007.

BERNARDO KRAUSE PAOLA CASANELLO ROBERTO REYES GERMAN EBENSPERGER

28 ACKNOWLEDGEMENTS Highlanders 2007 FFDD Payachatas NEWBORN LAMBS ANIBAL LLANOS RAQUEL RIQUELME EMILIO HERRERA EMILIA SANHUEZA BERNARDO KRAUSE PAOLA CASANELLO ROBERTO REYES GERMAN EBENSPERGER MARÍA CAPETILLO SERGIO GONZALEZ CARLOS BRITO MARIO MORALES GABINO LLUSCO ENRIQUE PEREZ

PULMONARY HYPERTENSION IN HIGH ALTITUDE NEWBORNS

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