title: Effects of propranolol on the cardiovascular and renin-angiotensin systems during hypotension produced by sodium nitroprusside in humans.
abstract: The authors examined the effects of controlled hypotension induced with sodium nitroprusside (SNP) with and without propranolol on the cardiovascular, pulmonary, and renin-angiotensin systems in 10 consecutive anesthetized patients with kyphoscoliosis undergoing posterior spinal fusion. SNP infusion (4.1 microgram . kg-1 . min-1) alone decreased mean systemic arterial pressure (SAP) by 25 torr +/- 3 SE (P less than 0.001), systemic vascular resistance index (SVRI) by 1113 dyne . sec. cm-5 . m2 +/- 125 SE (P less than 0.001), mean pulmonary artery pressure (PAP) by 6 torr +/- 2 SE (P less than 0.02), pulmonary capillary wedge pressure (PCWP) by 4 torr +/- 1 SE (P less than 0.01), pulmonary vascular resistance (PVR) by 50 dyne . sec . cm-5 +/- 18 (P less than 0.05), and PaO2 by 16 torr +/- 7 SE (P less than 0.05), whereas cardiac index increased by 1.08 l . min-1 . m2 +/- 0.24 SE (P less than 0.01) and heart rate increased 16 beats/min +/- 5 SE (P less than 0.02). After 40 min of hypotension, 0.03 mg/kg propranolol was injected intravenously while the SNP infusion rate was held constant. Ten min later there was a significant decrease in the heart rate (10 beats/min +/- 4 SE, P less than 0.02) and cardiac index (0.65 l . min-1 . m-2 +/- 0.21, P less than 0.02). Plasma renin activity (PRA) increased from 2.37 ng . ml-1 . h-1 +/- 0.7 SE before anesthesia to 6.50 ng . ml-1 . h-1 +/- 1.45 SE (P less than 0.05) after 40 min of nitroprusside infusion. Forty min after propranolol there was a significant reduction in PRA to 4.07 ng . ml-1 . h-1 +/- 0.73 SE (P less than 0.05). Thus propranolol, when given during SNP hypotension, exhibits an early cardiovascular response manifested as a decrease in cardiac output and heart rate and a delayed action of the kidney resulting in an inhibition of renin release.
mesh_terms: D000293:Adolescent; D000328:Adult; D000809:Angiotensins / Q000378:metabolism*; D002319:Cardiovascular System / Q000187:drug effects*; D006801:Humans; D007022:Hypotension / Q000139:chemically induced*; D008168:Lung / Q000187:drug effects; D009599:Nitroprusside; D011433:Propranolol / Q000494:pharmacology*; D012083:Renin / Q000097:blood*; D013123:Spinal Fusion
chemical_list: D000809:Angiotensins; D009599:Nitroprusside; D011433:Propranolol; D012083:Renin