Effects of left atrial receptor stimulation on carotid chemoreceptor-induced renal responses in dogs.

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1. Dogs were anaesthetized with thiopentone sodium and alpha-chloralose and artificially ventilated. The carotid sinus regions were vascularly isolated and perfused with arterial or venous blood to stimulate the chemoreceptors. Left atrial receptors were stimulated by distending four balloons, three in the left pulmonary vein-atrial junctions and one in the left atrial appendage. Mean aortic pressure was held constant by means of a pressure control device. Atenolol and atropine (2.0 and 0.5 mg kg-1, respectively), and gallamine triethiodide (3.0 mg kg-1 h-1) were given I.V. Renal blood flow was measured by an electromagnetic flowmeter, glomerular filtration rate by creatinine clearance, urinary sodium by flame photometry and solute excretion by osmometry. 2. In fifteen tests in eight dogs (in one dog responses of both left and right kidneys were determined), at a constant aortic pressure (AoP) of 92.0 +/- 3.2 mmHg, and carotid sinus pressure (CSP) of 95.0 +/- 2.0 mmHg, stimulation of left atrial receptors with balloon inflation resulted in significant increases in renal blood flow (RBF) by 8.3 +/- 0.9 from 255.0 +/- 14.6 ml min-1 (100 g kidney weight)-1 (n = 9), in glomerular filtration rate (GFR) by 4.1 +/- 0.6 from 21.2 +/- 1.9 ml min-1 (100 g)-1, in filtration fraction (FF) by 0.04 +/- 0.003 from 0.20 +/- 0.01, in urine flow rate (V) by 0.08 +/- 0.02 from 0.33 +/- 0.05 ml min-1 (100 g)-1, in sodium excretion (UNaV) by 4.4 +/- 0.9 from 27.7 +/- 4.2 mumol min-1 (100 g)-1, in osmolar excretion (UosmV) by 62.0 +/- 5.6 from 303.0 +/- 28.3 mu osmol min-1 (100 g)-1, and in a decrease in free water clearance (CH2O) by 0.13 +/- 0.03 from -0.63 +/- 0.04 ml min-1 (100 g)-1. Left atrial pressure (LAP) and heart rate (HR) did not change significantly from 6.9 +/- 0.3 cmH2O, and 133.0 +/- 3.4 beats min-1 respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

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