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P. Antonio Tataranni, Laurent Christin, Søren Snitker, Giuseppe Paolisso, Eric Ravussin, Pima Indian Males Have Lower β-Adrenergic Sensitivity Than Caucasian Males, The Journal of Clinical Endocrinology & Metabolism, Volume 83, Issue 4, 1 April 1998, Pages 1260–1263, https://doi.org/10.1210/jcem.83.4.4687
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The sympathetic nervous system controls cardiovascular homeostasis and regulates energy metabolism. Pima Indians, a population with a low prevalence of hypertension and a high prevalence of obesity, have low sympathetic nervous activity, compared with Caucasians. Preliminary findings suggest that they may also have a low β-adrenergic sensitivity. We studied β-adrenergic sensitivity in 87 nondiabetic normotensive individuals [52 Pima Indians (35 males/17 females) and 35 Caucasians (24 males/11 females)], matched for age and body weight. Chronotropic sensitivity to β-adrenergic stimulation was assessed by the dose of isoproterenol necessary to increase heart rate by 25 beats per minute [chronotropic dose-25 (CD25)]. Despite a similar basal heart rate and arterial blood pressure, Pimas tended to have lowerβ -adrenergic sensitivity than Caucasians (CD25 = 2.37 ± 2.27 vs. 1.57 ± 1.38 μg, P = 0.07; mean ± sd). This difference was significant in males (CD25 = 3.03 ± 2.39 vs. 1.85 ± 1.56μ g, P = 0.02) but not in females (CD25 = 1.01 ± 1.17 vs. 0.96 ± 0.61 μg, P = 0.99). In males only, CD25 was positively correlated to percent body fat (r = 0.36, P < 0.01). After adjustment for percent body fat, β-adrenergic sensitivity was still significantly lower in Pima than in Caucasian males (CD25 = 3.44 ± 2.24 vs. 2.57 ± 1.60 μg, P = 0.05). In conclusion, our data suggest that increased adiposity is accompanied by decreasedβ -adrenergic sensitivity in males only. However, at each level of adiposity, Pima Indian males have lower β-adrenergic sensitivity than Caucasian males. In combination with a low sympathetic nervous system activity, a reduced β-adrenergic sensitivity may contribute to the low prevalence of hypertension and the high prevalence of obesity observed in Pima Indians.
