Concentrations of 14 commonly-requested plasma hormones were measured in octuplicate in each of six subjects to determine their stability when unseparated from red cells for periods up to 1 week. Most of the analytes were stable when stored in this way and although statistically significant changes were recorded, in the great majority of cases the changes seen would have no bearing on the clinical interpretation of the result. In the light of these findings, we would confidently report results of analyses for these hormones in plasma that had remained in contact with red cells at ambient temperature for long periods of time.

The effects of norepinephrine (NE) and acetylcholine (ACh) on isometric force generation were studied in isolated helical strips of intrapulmonary arteries (IPA) and veins (IPV) (3-5 mm diam) from lungs of dog, sheep, swine, and man. Cummalative dose-effect relationships (10-minus8-10-minus 4 M) were determined. All strips contracted in a dose-related fashion when exposed to NE but responses of sheep and swineIPV were weak. Acetylcholine relaxed canine IPA and contracted human IPA, CANINEIPV, and sheep IPV in a dose-related manner. Sheep IPA and swine IPA and IPV were unresponsive to ACh. Human IPV were relaxed by ACh but this effect wasreversed at the highest concentration (10 minus 4 M) tested. All vascular stripscontracted well in a potassium-rich (127 mM) bathing medium. It is concluded thatintrapulmonary lobar vessels from man, dog, swine, and sheep are responsive to autonomicneurohormones but that quantitative as well as qualitative differences exist.

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