West African Journal of Medicine

Department of Pharmacology, Lagos State University College of Medicine, Ikeja, Lagos, Nigeria. Correspondence: T. A. John, Department of Pharmacology, Lagos State University College of Medicine, PMB 21266, Ikeja, Lagos. Email: [email protected] Tel: 234 7028338910 Abbreviations: SMC, Smooth muscle cell; CHAH, Chronic high altitude hypoxia; alpha SMA, alpha Smooth muscle actin; eNOS, endothelial Nitric oxide synthase; mRNA, messenger Ribonucleic acid; RT-PCR, Reverse transcription polymerase chain reaction; NO, Nitric oxide; vWF, von Willebrand factor. ABSTRACT BACKGROUND: The effect of chronic high altitude hypoxia (CHAH) in the juxta-alveolar region near the air-blood interface is unknown because of the experimental inaccessibility of this region. OBJECTIVE: To examine primary cultures of digested juxtaalveolar smooth muscle cells for hypoxia-induced changes. METHODS: Smooth Muscle Cells (SMCs) obtained by dispase digestion of the extreme lung parenchyma were used to study the effect of CHAH in the juxta-alveolar region and foetal and maternal cells were compared. Pulmonary venous SMCs were also obtained from dissected 5 to 7 generation levels pulmonary veins (<0.5 mm). Fluorescence tagged antibodies against alpha smooth muscle actin (alpha SMA) and calponin respectively were used as markers to identify cellular structural differences by routine immunohistochemistry. Comparison of the functional integrity of the cells was made using their growth profiles obtained by radiolabeled thymidine incorporation and liquid scintillation counting. RESULTS: Marked differences were seen in juxta-alveolar SMCs obtained by digestion of extreme lung parenchyma of hypoxic sheep. Hypoxic adult sheep cells showed increased filamentation. Hypoxic foetal sheep cells showed internal restructuring and disorganization of both alpha-SMA and calponin filaments. The growth profiles of juxta-alveolar SMCs showed that the hypoxia-affected cells of both the foetus and adult sheep had a fast initial growth rate peaking at 48h while their normoxic equivalents had a steadier growth rate peaking at 72h. Hypoxia-affected cells showed contact inhibition at ~50% subconfluence and apoptosis by 48h. CONCLUSION: Chronic high altitude hypoxia causes both phenotypical and functional changes in pulmonary smooth muscle cells near the air/blood interface. WAJM 2010; 29(6): 388–392.