scholarly journals EFFECTS OF CAFFEINE AND PROCAINE ON THE MEMBRANE AND MECHANICAL PROPERTIES OF THE SMOOTH MUSCLE CELLS OF THE RABBIT MAIN PULMONARY ARTERY

1977 ◽  
Vol 27 (4) ◽  
pp. 467-481 ◽  
Author(s):  
Yushi ITO ◽  
Hikaru SUZUKI ◽  
Hirosi KURIYAMA
Keyword(s):  
Mechanical Properties ◽  
Smooth Muscle ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Main Pulmonary Artery ◽  
Muscle Cells

Membrane properties of smooth muscle cells in pulmonary hypertensive rats

1982 ◽  
Vol 242 (5) ◽  
pp. H907-H915 ◽  
Author(s):  
H. Suzuki ◽  
B. M. Twarog
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Main Pulmonary Artery ◽  
Fold Increase ◽  
Muscle Cells ◽  
Membrane Properties ◽  
Resting Membrane Potential ◽  
Chronic Pulmonary Hypertension

The membrane properties of smooth muscle cells in rat main pulmonary artery (MPA) and small pulmonary artery (SPA) were investigated during chronic normobaric hypoxia and after monocrotaline injection. As chronic pulmonary hypertension developed, pronounced differences between MPA and SPA were observed. These findings may shed light on mechanisms of smooth muscle hypertrophy. 1) The resting membrane potential of smooth muscle in MPA became less negative than the normal (depolarized), whereas the resting membrane potential of smooth muscle in SPA became more negative (hyperpolarized). 2) In MPA, both the length and time constants diminished. 3) In MPA, the maximum membrane depolarization produced by a 10-fold increase in extracellular [K+] decreased. 4) In SPA, the depolarization observed in K+-free solution was more rapid and greater in amplitude, and the transient hyperpolarization following restoration of K+-containing solution increased. 5) In SPA, initial and sustained depolarization evoked by Na+-deficient solutions were increased. 6) Depolarization in MPA was due to increased membrane permeability, perhaps to Cl-, whereas hyperpolarization in SPA could be attributed to increased activity of an electrogenic Na+-K+ pump.

Membrane properties of smooth muscle cells in pulmonary arteries of the rat

1982 ◽  
Vol 242 (5) ◽  
pp. H900-H906 ◽  
Author(s):  
H. Suzuki ◽  
B. M. Twarog
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Main Pulmonary Artery ◽  
Pulmonary Arteries ◽  
Outward Current ◽  
Muscle Cells ◽  
Membrane Properties ◽  
Similar Degree

Electrical properties of the membrane of smooth muscle cells in the rat main pulmonary artery (MPA) and a small pulmonary artery (SPA) were compared. MPA and SPA differed in several important respects, suggesting characteristic quantitative and qualitative differences in membrane properties. 1) Resting membrane potentials were similar in both (MPA 52.2 +/- 1.3 mV; SPA 51.5 +/- 1.7 mV). The cells displayed no spontaneous electrical activity. The muscle layers in both MPA and SPA showed cablelike properties; a graded local response to outward current pulses was observed, but no action potentials were evoked. 2) Tetraethylammonium chloride (TEA, 1-5 mM) depolarized, increased membrane resistance, and suppressed rectification in MPA. TEA strongly depolarized SPA and contraction ensued. 3) The maximum membrane depolarization produced by a 10-fold increase in extracellular [K+] was 48 mV in MPA and 47 mV in SPA. In K+-free solution gradual depolarization was observed in SPA, but the membrane potential in MPA was not modified. Restoration of K+-containing solution produced equivalent hyperpolarization in both tissues, indicating a similar degree of stimulation of electrogenic Na+-K+ pumping. 4) A Na+-deficient solution did not affect the membrane potential in MPA but depolarized SPA.

scholarly journals Free radical production in hypoxic pulmonary artery smooth muscle cells

2000 ◽  
Vol 279 (2) ◽  
pp. L408-L412 ◽  
Author(s):  
David W. Killilea ◽  
Raymond Hester ◽  
Ronald Balczon ◽  
Pavel Babal ◽  
Mark N. Gillespie
Keyword(s):  
Smooth Muscle ◽  
Free Radical ◽  
Pulmonary Artery ◽  
Smooth Muscle Cells ◽  
Main Pulmonary Artery ◽  
Muscle Cells ◽  
Exposure System ◽  
Free Radical Production ◽  
Radical Production ◽  
Pulmonary Artery Smooth Muscle

This study used an inexpensive and versatile environmental exposure system to test the hypothesis that hypoxia promoted free radical production in primary cultures of rat main pulmonary artery smooth muscle cells (PASMCs). Production of reactive species was detected by fluorescence microscopy with the probe 2′,7′-dichlorodihydrofluorescein, which is converted to the fluorescent dichlorofluorescein (DCF) in the presence of various oxidants. Flushing the airspace above the PASMC cultures with normoxic gas (20% O2, 75% N2, and 5% CO2) resulted in stable Po 2 values of ∼150 Torr, whereas perfusion of the airspace with hypoxic gas (0% O2, 95% N2, and 5% CO2 ) was associated with a reduction in Po 2 values to stable levels of ∼25 Torr. Hypoxic PASMCs became increasingly fluorescent at ∼500% above the normoxic baseline after 60 min. Hypoxia-induced DCF fluorescence was attenuated by the addition of the antioxidants dimethylthiourea and catalase. These findings show that PASMCs acutely exposed to hypoxia exhibit a marked increase in intracellular DCF fluorescence, suggestive of reactive oxygen or nitrogen species production.

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