The response in blood non-esterified fatty acids (NEFA) to an adrenergic stimulation was studied in rabbit does. Two separate experiments were carried out to find the best time interval for blood sampling after an adrenergic stimulation and to find the appropriate dose for the challenging stimulus. In the first experiment, the time evolution was studied by injecting 9 animals intravenously with 50 mg of isoproterenol per kg of live weight (LW), blood being collected just before and 5, 10, 15, 20, 30 and 40 minutes after challenge. The highest NEFA responses, calculated as the difference between NEFA concentration in samples taken before and after adrenergic stimulation, were observed at 5 and 10 minutes after challenge (+0.70±0.15 and +0.77±0.15 mmol/L, respectively). In the second experiment, 6 animals were consecutively injected with isoproterenol (0.5, 5 or 50 mg/kg LW) and placebo (NaCl, 0.9%) with an interval of 1 hour; and blood was sampled just before and 7.5 minutes after challenge. The NEFA responses were significantly different from zero only when isoproterenol was injected at the dose of 50 mg/kg LW. Thus, we concluded that, among the tested dose concentrations of isoproterenol, 50 mg/kg LW was the most useful dose for adrenergic stimulation and that the adrenergic response was highest at 5 and 10 minutes after challenge.
rabbit; adrenergic stimulation; non-esterified fatty acids; dose response; time response