The regional distribution of the peripheral vascular resistance was studied in normotensive and hypertensive Wistar rats. Two models of experimental hypertension were investigated: (I) in 32 animals the right renal artery was constricted by a silver clip (two-kidney Goldblatt hypertension); (II) in 46 animals the left kidney was removed and the right renal artery was clipped as in the first group (one-kidney Goldblatt hypertension). The normotensive control group comprised 61 untreated animals of the same strain and age. The distribution of cardiac output to 14 tissues was determined by means of the particle distribution technique. The resistance was increased in all regions investigated, a decreased or unchanged resistance was not observed. For most of the investigated tissues the regional resistance was increased exactly in proportion to the total peripheral resistance (TPR). Exceptions to this were found in 2 regions where the change of local resistance deviated from that of TPR: the splanchnic area and the skeletal muscle. In both cases the 2 models differed from each other. In the two-kidney model the increase of resistance in the splanchnic circulation was more intense than in other organs. In contrast, in the one-kidney model the local change of resistance was less than that of TPR. The change of skeletal muscle resistance was not significantly different from the change of TPR in the two-kidney model, while in the one-kidney model the increase of local resistance was significantly higher than that of TPR. It is concluded that the etiology of the abnormal resistance is different in the 2 models investigated and that known extrinsinc pressor factors may play a role in the two-kidney, but not in the one-kidney Goldblatt hypertension.

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The effect of intravenous infusion of dopamine (10 and 25 micrograms X kg-1 X min-1 consecutively) on visceral blood flow distribution was examined in anesthetized cats using the microsphere technique and electromagnetic flowmetry. Arterial blood pressure did not change in response to dopamine infusion, but blood flow through the superior mesenteric artery, and blood flow in the mucosa-submucosa of the gastric antrum and various gut segments increased significantly. During infusion of the high dose the increase was most marked in the mucosa-submucosa of the antrum (+355%) and distal colon (+371%). By contrast, blood flow decreased in the muscularis-serosa of the gut segments investigated, in the spleen, pancreas, and the hepatic arterial bed. The increase in blood flow through the superior mesenteric artery was blocked by the dopamine antagonist bulbocapnine (10 mg/kg i.v.). The results suggest that the receptors mediating the dopamine-induced vasodilation in the gastrointestinal tract are located in the resistance vessels of the mucosa-submucosa.

To examine the 2-deoxyglucose (2-DG)-method for myocardial tissue, glucose uptake was measured directly and via the 2-DG-technique in 16 isolated perfused guinea pig hearts. A correlation (r = 0.7; p less than 0.01) between both methods was found. In the in situ working canine heart 2-DG revealed a 20% higher glucose uptake of the subendocardial layers as compared with the subepicardial. Blood flow to these layers, estimated by albumin aggregates, exceeded that to the subepicardial by 82%. Thoracotomy resulted in a homogeneous distribution of blood flow and tissue PO2, comparable to a homogeneous distribution of glucose uptake in isolated perfused hearts.