Pulmonary function and oxygen transfer was studied in five patients with cirrhosis of the liver and different degrees of portasystemic encephalopathy. Four patients were restudied after a change in CNS function. The contribution of various parameters of pulmonary gas exchange to the unsaturation found was evaluated employing the graphic analysis described by King and Briscoe. The following results were obtained: (1) there was no inequality of ventilation as judged by a nitrogen washout study; (2) a large true venous admixture was found in all patients; (3) in four patients studied twice venous admixture was larger when mean EEG frequency was lower; (4) besides the true venous admixture a low overall D/Q ratio was an important factor contributing to unsaturation in most cases; (5) in some cases a decreased overall V/Q ratio contributed to the unsaturation. This decreased V/Q ratio appeared to be due to an increase in pulmonary perfusion without a concomitant rise in ventilation. Changes in pulmonary perfusion pathways are suggested as the most likely cause of the defect in oxygen transfer found in patients with cirrhosis.
Potassium channels present in the basolateral membrane of respiratory epithelial cells play an important role in the process of chloride secretion. Utilizing the patch clamp technique, we examined human cultured respiratory epithelial cells derived from patients with cystic fibrosis (CF) and normals individual (N) for the existence of and for the properties of K+ channels. We obtained qualitatively and quantitatively identical results for both preparations (CF and N). K+ channels were spontaneously present in cell attached patches. The channels showed burst appearance with rapid flickering within the bursts. When the pipette was filled with 145 mmol/l KCl, a mean conductance of 131 +/- 25 pS (n = 15) was read from the I/V-curve at a clamp voltage (Vc) of 0 mV. After excision, the conductance read from the I/V-curve at Vc = 0 mV was 212 +/- 11 pS (Pipette: 145 mmol/l KCl, bath: 145 mmol/l NaCl) (n = 61). With NaCl in the pipette and KCl in the bath, a similar conductance was obtained (g = 210 pS; n = 2). When both, pipette and bath contained KCl, the conductance was increased to 302 +/- 19 (n = 7). The channel was highly selective for potassium over sodium: PK + /PNa + greater than 40. The channel open probability was only slightly voltage dependent i.e. the open probability increased slightly with depolarisation. For most of the channels one open time constant (to = 6.3 +/- 1.6 ms; n = 22) and one closed time constant (tc = 1.8 +/- 0.3 ms; n = 21) was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)
Patients with cirrhosis of the liver frequently have an increased cardiac output *l and diminished systemic vascular ~e s i s t a n c e .~~~~~~~ This hyperkinetic circulatory state probably represents a response to a decrease in systemic vascular resistance. The existence of a circulating vasodilating substance has been suggested as a possible cause. The available evidence would indicate that it must be affecting the vascular system at various sites. It could be responsible for an admixture of venous to arterial blood since arterial oxygen unsaturation was found in about one-third of patients with hepaticThe possibility of anastomoses between the pulmonary veins and either the pulmonary artery or the portal venous system has been discussed repeatedly. To investigate further the relationships between portal hypertension and pulmonary circulation as the possible basis for arterial oxygen unsaturation, we have done some studies during the administration of histamine which is known to be a potent vasoactive material.
Special InvestigationsStudy 1
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