Basal levels of plasma epinephrine and norepinephrine in the dog.

Abstract

SUMMARY Conscious (n = 62) and anesthetized (n = 34) dogs were studied to establish basal levels and ranges for plasma epinephrine (E) and norepinephrine (NE) in this species. Trained conscious dogs were familiarized to recording conditions and personnel for 2 to 3 weeks and acclimatized to the laboratory for at least 15 minutes prior to blood sampling from a chronically implanted catheter. Their basal values were 65 ± 47 pg/ml for E and 145 ± 58 pg/ml for NE, which were significantly lower (p < 0.05) than values in a second group of conscious dogs trained in the same manner but sampled soon after arrival to the laboratory (E = 144 ± 93 pg/ml; NE = 193 ± 86 pg/ ml). Catecholamine levels in dogs anesthetized with one of three different regimes commonly used in cardiovascular studies were shown to be similar to the basal values found in conscious dogs acclimatized to the laboratory. The weak correlations found between basal plasma catecholamines and hemodynamic variables in all groups of conscious dogs reflect the complexity of factors interacting with the sympathetic nervous system in the maintenance of arterial pressure. These results document the variability that can be expected when using catecholamine levels as an index of sympathetic nervous system activity and the necessity of standardizing conditions for sample collection. (Hypertension 5 (supp V): V-128-V-133, 1983)KEY WORDS • catecholamines • canine sympathetic nervous system activity heart rate * blood pressure A CCURATE determination of basal levels of catecholamine concentrations in plasma is essential to assess the physiological significance of an experimental challenge in any species' particularly when these measurements are used to gauge the degree of sympathetic nervous system activation. In dogs, reported values for basal catecholamine levels are variable, 1 " 3 and this may reflect methodological inconsistencies in either sampling, in assay procedures, or both. We report here a population study conducted in dogs assessing basal plasma levels of E and NE from blood samples collected over a 3-year period. A sensitive radioenzymatic assay was performed on plasma samples collected in association with rigorously standardized animal training and blood sampling techniques. Methods Physiological ProceduresNinety-six normal male mongrel dogs weighing between 16 and 30 kg were used in these experiments. Five groups were compared. Group 1Conscious, trained, resting-recumbent dogs (n = 17) were trained according to conditions established in the laboratory for the chronic characterization of resting arterial pressure.4 " 6 Experiments were started 2 to 3 weeks after the dogs were instrumented with a catheter chronically positioned into the lower abdominal aorta via an iliac artery. During the recording and sampling session, dogs were housed in a pen in a dimly lit laboratory and shielded from ambient visual and auditory stimuli. Blood pressure and heart rate (HR) were recorded for 60 to 90 minutes. The dogs were acclimatized to recording conditions at least...

Norepinephrine kinetics in dogs with experimentally induced renal vascular hypertension

“…Therefore, the decrease in renal hemodynamics that we detected was relatively fixed and stable, compared with that determined in a study of dogs with hypertension induced by use of the 2K1C model. 20 In our study, mean (± SD) plasma NE concentration during the control period was 151.5 ± 28.3 pg/ml, which was similar to concentrations reported in studies of trained conscious dogs (145 ± 58 pg/ml 21 and 120 to 145 pg/ml 4 ). Analysis of these data suggests that dogs in the study reported here were trained and acclimatized sufficiently to the laboratory environment such that NE concentrations did not increase as a result of necessary manipulations.…”

In a Canine Model of Septic Shock, Cardiomyopathy Occurs Independent of Catecholamine Surges and Cardiac Microvascular Ischemia

“…In these septic and non-septic controls catecholamine levels remained within, or very near, the normal range for anesthetized canines throughout the study. 19 However, we found that myocardial depression still occurred. In septic animals compared to non septic controls, profound highly significant drops in LVEF and significant worsening of circumferential strain and ventricular-aortic coupling occurred over two days, which occurred in the absence of increased endogenous and exogenous catecholamines.…”

“…After bacterial challenge (T0), in the absence of exogenous catecholamine administration, serial plasma epinephrine, norepinephrine, and combined catecholamine levels were within or slightly above the normal range for sedated otherwise healthy canines (Figure 2, Panel A-C). 19 Specifically, the only elevations in catecholamine levels above the normal range occurred in the plasma norepinephrine concentration of septic animals. In these animals, the elevations occurred transiently and were only minimally above the upper limit of normal (Figure 2, Panel B) for sedated animals.…”

“…Normal mean values and ranges for sedated canines for these catecholamines were obtained through the literature. 19 In Panel D, individual animals’ changes from baseline to 48 hours in LVEF as measured by CMR were compared to the levels of endogenous catecholamines over 48 hours (AUC) for septic animals and controls.…”