In canine adipose tissue, adrenaline exerts a greater constrictor effect on precapillary sphincters and capacitance vessels compared to felypressin at doses producing similar flow reductions.
Adrenaline's microvascular effects in canine adipose tissue should not guide clinical vasopressor choice; leaves open differential precapillary actions in human physiology.
Blood flow and tissue volume were recorded in the isolated canine subcutaneous adipose tissue, enclosed in a plethysmography. Adrenaline and felypressin (octapressin) were infused intra-arterially at doses producing a blood flow reduction of approximately 60%. Adrenaline (4.6-23 ng/min) caused an initial reduction in tissue volume, indicating a constriction of capacitance vessels. Octapressin (0.46-9.2 ng/min) had no effect on tissue volume. Neither adrenaline or octapressin caused appreciable filtration or absorption, suggesting that the pre- to postcapillary resistance ration remained unchanged. In contrast to sympathetic stimulation and noradrenaline, adrenaline significantly reduced the capillary filtration coefficient (CFC) by 34%, the change in CFC being related to the flow reductions, while octapressin did not reduce CFC sffect of adrenaline on precapillary sphincter sections and on capacitance vessels is greater than that of octapressin in doses producing similar flow reductions.
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Burcher et al. (1977) studied this question.
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