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Single rapid and deep inspirations (inspiratory gasps, IG) result in arteriolar vasoconstriction with concomitant transient decreases in skin blood flow that are most prominent in fingers and toes. Vascular responses (inspiratory gasp responses, IGR) are determined as the maximum percentage reduction in blood flow and have been used to assess sympathetic neurovascular function in several conditions. Previous studies have described various features of the response but there has been no reported systematic investigation of the degree of similarity between IGR obtained on dominant and non-dominant hands. This aspect is important in procedures that may use IGR to evaluate suspected unilateral sympathetic dysfunction of a limb-pair or to test the effectiveness of physiological interventions imposed on a single limb of a pair. Thus, the goal of our study was to compare IGR magnitudes that were simultaneously determined in paired-fingers of dominant and non-dominant hands. In 30 healthy seated subjects, skin blood perfusion via laser-Doppler (SBF) was measured on the dorsum of the middle finger of both hands while subjects performed three sequential IG at 3-min intervals. Analysis of variance for repeated measures revealed no significant difference in IGR between dominant (79·3 ± 11·2%) and non-dominant hands (81·9 ± 11·6%,P = 0·965) with an overall IGR of 80·6 ± 11·4%. These results indicate that hand-dominance is not a factor that is likely to significantly effect IGR differentials determined in paired-limbs. [ABSTRACT FROM AUTHOR]

Abstract: Our specific aim was to investigate whether a local static magnetic field of a permanent magnet, of either pole, affects resting skin blood perfusion. This was done by measuring skin blood perfusion (SBF) by laser-Doppler in dorsum skin of 2nd and 4th fingers of the nondominant hands of 12 volunteers. Both fingers were first exposed to sham magnets, and then the 2nd finger was exposed alternately to north and south poles of a neodymium magnet that produced a field of 4024 G at the palmar part of the finger and a field of 879 ± 52 G at the site of finger dorsum SBF measurement. Each of the three exposure intervals was 15 min. SBF values were analyzed by first computing the average SBF during the last 5 min of each of the three 15-min exposure intervals. These SBF averages were initially tested for magnet or magnet-pole effects by analysis of variance for repeated measures with finger as a factor, using SBF values for each finger as the test variable. Results of this analysis revealed a large variability in finger SBF among subjects and no significant difference in SBF between exposure conditions (P = 0.705) or any significant interaction between SBF and finger (P = 0.396). However, when intersubject variability was reduced by using the flow difference between treated and nontreated fingers in each exposure interval as the test variable, a statistically significant effect (P = 0.016) attributable to magnet exposure was uncovered. This effect was a reduction in resting SBF in the magnet-exposed fingers that was similar for north and south pole magnet exposure. The present findings are the first to demonstrate a direct effect of locally applied magnets on human skin blood perfusion. [Copyright &y& Elsevier]