A 64-year-old man was admitted to the hospital for evaluation of progressive dyspnea and increasing angina. The medical history was significant for coronary artery disease with an uncomplicated myocardial infarction 8 years ago. Diabetes was diagnosed 10 years ago and was controlled currently with diet alone. Peripheral vascular disease necessitated a left below-the-knee amputation 2 years ago. Although previously a "heavy" smoker, he had stopped smoking 5 years ago. Current medications included furosemide, persantine, and digoxin. Physical examination revealed a blood pressure of 120/76 mm Hg; pulse, 82 beats/mm and regular; and respirations, 24/mm. No jugular venous distension was present. The chest had bibasilar rales. Cardiac examination was unremarkable. There was no abdominal organomegaly. External genitalia and rectal examination were unremarkable, A sensory-motor peripheral neuropathy was present. Laboratory data on admission included: sodium, 138 mEq/liter; potassium, 5.5 mEq/liter; chloride, 109 mEq/Iiter; and carbon dioxide, 22 mEq/liter. The BUN was 68 mg/dl and the creatinine 3.8 mgldl. Glucose was 123 mg/dl. Urinalysis revealed 3+ albumin, trace glucose, 6—9 white blood cells/high-power field, and no casts. An electrocardiogram showed normal sinus rhythm and evidence of an old, anteroseptal myocardial infarction. A plain chest film disclosed small bilateral pleural effusions and changes of chronic obstructive pulmonary disease. Renal ultrasound examination was normal. The 24-hour creatinine clearance was 26 mI/mm. Urine protein excretion was 5.8 g/24 hours. The patient was scheduled for coronary angiography. Prior to angiography he received 1000 ml of 0.45% saline over 10 hours, which was