Vascular responses of the extremities to transdermal application of vasoactive agents in Caucasian and African descent individuals

This is an accepted manuscript of an article published by Springer in European Journal of Applied Physiology on 04/04/2015, available online: https://doi.org/10.1007/s00421-015-3164-2 The accepted version of the publication may differ from the final published version.© 2015, Springer-Verlag Berlin Heidelberg. Purpose: Individuals of African descent (AFD) are more susceptible to non-freezing cold injury than Caucasians (CAU) which may be due, in part, to differences in the control of skin blood flow. We investigated the skin blood flow responses to transdermal application of vasoactive agents. Methods: Twenty-four young males (12 CAU and 12 AFD) undertook three tests in which iontophoresis was used to apply acetylcholine (ACh 1 w/v %), sodium nitroprusside (SNP 0.01 w/v %) and noradrenaline (NA 0.5 mM) to the skin. The skin sites tested were: volar forearm, non-glabrous finger and toe, and glabrous finger (pad) and toe (pad). Results: In response to SNP on the forearm, AFD had less vasodilatation for a given current application than CAU (P = 0.027–0.004). ACh evoked less vasodilatation in AFD for a given application current in the non-glabrous finger and toe compared with CAU (P = 0.043–0.014) with a lower maximum vasodilatation in the non-glabrous finger (median [interquartile], AFD n = 11, 41[234] %, CAU n = 12, 351[451] %, P = 0.011) and non-glabrous toe (median [interquartile], AFD n = 9, 116[318] %, CAU n = 12, 484[720] %, P = 0.018). ACh and SNP did not elicit vasodilatation in the glabrous skin sites of either group. There were no ethnic differences in response to NA. Conclusion: AFD have an attenuated endothelium-dependent vasodilatation in non-glabrous sites of the fingers and toes compared with CAU. This may contribute to lower skin temperature following cold exposure and the increased risk of cold injuries experienced by AFD.Published versio

NUCLEAR CARDIOLOGY, CURRENT APPLICATIONS IN CLINICAL-PRACTICE

The clinical applications of nuclear cardiology have rapidly expanded since the introduction of suitable imaging cameras and readily applicable isotopes. The currently available methods can provide useful data on estimates of ventricular function and detection of myocardial ischemia for adequate patient management. Two standard procedures are routinely used: (1) myocardial perfusion scintigraphy, eg, with thallium 201; and (2) radionuclide angiocardiography by using technetium 99m-labeled red blood cells. Myocardial perfusion scintigraphy provides information on regional viability and estimates regional myocardial perfusion by measuring regional tracer activity. Thallium 201 is the agent used for noninvasive assessment of myocardial perfusion and for improving the results of exercise electrocardiography. Alternative tests, such as pharmacologic stress testing with dipyridamole, have been proposed as a reliable substitute for exercise testing. Additional quantitative analysis and computed tomography have increased the sensitivity and specificity of thallium scintigraphy. Radionuclide angiography techniques are used for the noninvasive evaluation of cardiac function, right and left ventricular function, and wall motion abnormalities. As in perfusion scintigraphy, radionuclide angiography has proven its value for the detection of coronary artery disease (CAD). Abnormal regional wall motion abnormalities are specific for CAD