Cholecystokinin peptides in cerebrospinal fluid: a study in healthy male subjects lumbar-punctured without preceding strict bed-rest

In a recent study we analysed the concentrations of two forms of cholecysto kinin (CCK), CCK-8S (sulphated) and CCK-4 in cerebrospinal fluid (CSF) obta ined from 14 healthy male volunteers lumbar-punctured after a minimum of ei ght hours of strict bed-rest. We have now lumbar-punctured another group of 14 healthy males: using the s ame procedure except for the requirement of strict bed-rest prior to punctu re. In contrast to our previous study, the concentration of CCK-4 (but not CCK- 8S) was significantly higher in the second CSF fraction (7-12 mi) than in t he first one (0-6 ml). On using the concentration ratio between the second and first fraction, CCK-8S (but not CCK-4) correlated positively with the a tmospheric pressure, which is in contrast to our previous study in which a significant negative correlation was found. When the lumbar CSF concentrations were expressed as the concentration per minute of tapping-time (an estimate of the mass flow), atmospheric pressure , age and the neuraxis distance in the lying position made significant cont ributions to the variance in CCK-8S. A significant positive correlation wit h atmospheric pressure was found for CCK-4. In conclusion, the results indicate that the question of strict bed-rest or not prior to lumbar puncture may have to be considered when interpreting d ata on lumbar CSF concentrations of CCK. A controlled study is warranted.