AUTOREGULATION AND VENO-VASOMOTORIC REACTION IN SPLENIC CIRCULATION

The occurrence of autoregulation (AR) and veno-vasomotoric reaction (VVR) in splenic circulation is described-to our knowledge for the first time. While AR only seldom showed high performance, VVR was as strong as observed in the intestinal circulation. Reproducible AR was demonstrated by only 4 out of 12 cats; 12 of the 54 measured flow-pressure (IP) curves exhibited the criteria of AR. On the other hand, reproducible positive reaction of VVR was indicated by 10 out of 12 tested cats in 30 of 40 averaged reactions. In order to express the strength of the reactions quantitatively, AR was evaluated in terms of the quotient QA, obtained from the value of the resistance of the vessel at 140 mm Hg divided by the value obtained at 70 mm Hg. AR is then indicated by QA>1. Due to the prevalence of the passive curves, however, in splenic circulation an avarage value of QA=0,787 was found; whereby the only 12 cycles with AR showed QA=1,148. UA, a quotient indicating the percentage of increase in resistance per mm Hg of arterial pressure increase, amounted for the mean of autoregulation reactions to +0,21. VVR was also expressed in terms of a quotient (Qv which is given by the relationship of the resistance R2 during venous pressure elevation (33 mm Hg) and control resistance R1. Qv>1 is again indicative of active reaction. From all of the determined 40 cycles within an arterial pressure range of 70-140 mm Hg, an avarage Qv=1,264 was obtained. This corresponds to an increase of 26.4% in resistance. In single cases, however, increases of resistance of over 100% were noted (Qv<2). Uv, a quotient indicating the percentage of increase in resistance per mm Hg of venous pressure elevation, amounted for active reactions to +1,11. In comparison with corresponding values of intestinal circulation, the high degree of dissociation of AR and VVR might probably be caused by the special structure of these circulatory vessels. Altogether it has been shown, that the arterial inflow of the spleen is controlled to a much higher degree from portal than from arterial systemic pressure. © 1969 Springer-Verlag.