Binding of exogenous noradrenaline by the proteins of dog plasma

Summary On addition to dog blood or plasma about 40% of exogenous nor-adrenaline escaped detection by photofluorimetric methods, when noradrenaline was present in concentrations ranging from 10 to 1000 ng/ml. As shown by bioassay the missing noradrenaline was not inactivated, but rather bound to plasma proteins; this was shown by experiments using labelled noradrenaline and precipitation of proteins, or Sephadex gel filtration. Cellulose acetate electrophoresis demonstrated binding by all protein fractions, alpha 1 and 2 globulins showing the greatest avidity for noradrenaline. Drugs known to be highly bound by proteins did not affect the binding capacity for noradrenaline. It is concluded that plasma noradrenaline values found after injection or infusion of noradrenaline may be only about half of the real values.Supported by Instituto de Alta Cultura (Research Project PMC-2).     

Studies into human IF secretion

There is a significant correlation between intrinsic factor (IF) and HCI content in 2-hour gastric aspirates after maximal stimulation with betazole. This correlation is due only in part to the fact that IF and HCI values from each subject are derived from the same volumes of gastric juice. There is an exception to this correlation among acid hypersecretors; their IF output is elevated to a lesser order of magnitude. Mean IF secretion by groups of elderly subjects is less than mean IF secretion by groups of younger subjects. However, an analysis of individual results shows that some elderly males can secrete as much IF as younger men. This suggests that reduced IF secretion is not an inevitable consequence of senescence. Preliminary evidence is presented which suggests that vagotomy may reduce betazole-stimulated IF secretion in most patients by a comparable amount as it reduces HCI secretion; IF secretion is not reduced in a minority of patients.     

Mitral regurgitation measured by continuous infusion of xenon An evaluation of the method in 91 patients

Mitral regurgitant flow levels and fractions were measured in 91 patients using a constant infusion of ¹³³xenon solution as an indicator. Regurgitant flow measurements ranged from 0.01 to 11.8 liters/min. Uniformity of left atrial mixing and negligible recirculation was achieved. The ¹³³xenon method was compared with other methods of measuring mitral regurgitation. This convenient technique was of great assistance in reaching conclusions about patients with mixed mitral stenosis and regurgitation, multiple valve replacement or mitral regurgitation associated with myocardial disease. We conclude that, because of the few sources of error and its clinical reliability, the ¹³³xenon method is one of the most accurate available.