| Abstract: | Previous studies on intact human subcutaneous tissue have shown, that blood flow remains constant during minor changes in perfusion pressure. This so-called auto regulatory response has not been demonstrable in isolated preparations of adipose tissue. In the present study on isolated, denervated subcutaneous tissue in female rabbits only 2 of 12 expts. revealed an auto regulatory response during reduction in arterial perfusion pressure. Effluent blood flow from the tissue in the control state was 15.5 ml/100 g·min (S.D. 6.4, n = 12) corresponding to slight vasodilatation of the exposed tissue. Following total ischemia all experiments showed a period with reactive hyperemia, and both duration of hyperemia and excess flow was related to the duration of the ischemia. This response therefore seems more resistant to the experimental procedure, while auto regulation of blood flow to lowered pressure is more susceptible to surgical exposure of the tissue. During elevation of arterial perfusion pressure blood flow in the isolated tissue showed a transient increase and then almost returned to the level during normotension, indicating an elevated vascular resistance. Raising of venous pressure elicited vasoconstriction with pronounced flow reduction. These two reactions may be important for local regulation of blood flow in subcutaneous tissue during orthostatic changes in arterial and venous pressure. It is concluded that the response in adipose tissue to changes in arterial pressure (auto regulation), venous pressure and total ischemia appear to be elicited by different mechanisms. |
