Rapid renal clearance of immunoreactive canine plasma myoglobin.

Abstract

SUMMARY Rates and mechanisms of myoglobin removal from plasma were examined in closed-chest dogs, using disappearance patterns of immunoreactivity and radioactivity after i.v. canine myoglobin radiolabeled with '"I. Arterial immunoreactive myoglobin concentration decreased monoexponentially over a 2-decade range, with rate constants of disappearance averaging 0.080 i 0.014 min-' (i SD) (corresponding to half-times of disappearance of 8.9 ± 1.5 mmn). Renal SERUM MYOGLOBIN concentration is elevated abnormally in the early phase of myocardial infarction in almost all patients seen within 12-14 hours of the onset of chest pain.14 Elevations in myoglobin frequently precede elevations of creatine kinase (CK); Stone et al.5 reported that 45% of infarct patients show increased myoglobin levels with normal CK levels at the time of admission. Elevated myoglobin levels peak earlier and return toward normal more rapidly than elevated CK levels. Myoglobin concentration-time curves sometimes show multiple peaks during the first several hours of apparently uncomplicated infarction.9Although the basis for these differing patterns of myoglobin and CK elevation has not been defined, a difference in a rate of removal from serum is an important possibility. CK disappearance from the intravascular space has been characterized.10 Although similar information for myoglobin is not available, myoglobin disappearance rates may be faster than those for CK; the kidney may play an important role."1'-4 If it does, sequential measurements of serum myoglobin may be useful for defining patterns of protein entry into the intravascular space during ischemic syndromes. Patients in the early states of myocardial injury -who may be the ideal candidates for interventions intended to minimize myocardial injury -might be identified as those with a normal serum myoglobin level on admission or a rapidly rising serum myoglobin over an interval of a few hours.The present study was designed to define rates and mechanisms of clearance from the circulation of a bolus of radiolabeled myoglobin administered intravenously. The studies capitalized on the sensitivity of recently developed radioimmunoassay techniques for quantifying plasma myoglobin concentration. The immunoassay also offered the opportunity to contrast changing patterns of plasma immunoreactivity and radioactivity, the former presumably reflecting disposition of the native molecule and the latter catabolic byproducts circulating within the vascular space as well as the native molecule. MethodsCanine myoglobin for exogenous administration and preparation of anti-dog myoglobin antibody was purified in a fashion similar to that for human myoglobin.6 Sequential steps included homogenization of canine myocardium in buffered saline, centrifugation and isolation of the supernatant, precipitation of protein with 50% ammonium sulfate, repeat centrifugation with dialysis of the supernatant against saturated ammonium sulfate, dissolution of the precipitate with subsequent dialysis against 0.02 M phosphate ...

Cardiac Troponins as Indicators of Acute Myocardial Damage in Dogs

“…The myocardial damage as a sequela of GDV is further supported by the significantly high CK-MB in all GDV dogs and increased myoglobin in 93% of these dogs in the absence of obvious skeletal muscle damage. Myoglobin and CK-MB are considered short-lived and nonspecific compared with cardiac troponins, with a half-life of approximately 9 minutes (myoglobin) 32 and 2 hours (CK-MB) 33 in dogs. The skeletal muscle damage due to surgery is a possible explanation for the absence of a decrease in myoglobin concentrations and a delayed decrease in CK-MB in GDV dogs.…”

Post-exercise vitamin C supplementation and recovery from demanding exercise

“…The results of the present study suggest that myoglobin is released more rapidly than CK, which may be due to the considerable size difference between these molecules. Furthermore, myoglobin is cleared within a few minutes from the circulation (Klocke et al 1982), whereas the half-life for CK is approximately 15 h (Neumeier et al 1981). Consequently, it is unlikely that post-exercise VC supplementation would have had any effect on serum myoglobin concentrations within 1 h of exercise, or serum CK activity on the day of exercise.…”

Biomonitors of cardiac injury and performance: B-type natriuretic peptide and troponin as monitors of hemodynamics and oxygen transport balance

“…Free troponin T and bound troponin T are relatively large molecules (37 and 77 kDa, respectively), similar in molecular weight to albumin (60 kDa), making it improbable that the kidney would be responsible for their clearance. Creatine kinase and its isoforms are of similar size and are mainly cleared by the reticuloendothelial system (123), whereas myoglobin is smaller (18 kDa) and cleared by the kidney (124). Indeed, in asymptomatic hemodialysis patients, troponin T rises in parallel with left ventricular mass and mirrors declining left ventricular systolic function (125).…”