Alpha-tubulin served as the loading control

0.05. Multivariable linear regression with change in systolic blood pressure, HR, and percent maximal predicted heart rate achieved at peak exercise as outcome variables was performed for non-coffee drinkers, subjects exposed to coffee 12 to 24 hours and more than 24 hours before regadenoson administration. Exposure to coffee 12 to 24 hours prior was used as the reference category. Adjustment for known confounders was based on clinical variables known to affect caffeine metabolism, as well as clinical variables with p<0.1 in univariable analysis and if adjustment for the variables resulted in at least a 10% change in the estimate of the overall association. Results Baseline characteristics of the study subjects are described in. Subjects mean age was 6011 years. Among the subjects, 257 were coffee drinkers while 73 subjects denied any coffee consumption. Non-coffee drinkers tended to be younger, more obese, consumed less chocolate, had more GERD and were less frequently prescribed antiplatelet medication as compared to coffee consumers. Twelve coffee drinkers did not report when they last consumed coffee. None of the subjects was taking theophylline. 3/9 Caffeine and Regadenoson Response Angiotensin-converting enzyme inhibitor. ARB: Angiotensin receptor blocker 1 2 3 4 Comparison between non-coffee drinker and subject who drank coffee 1224 hours prior Comparison between non-coffee drinker and subjects who drank coffee more than 24 hours prior Comparison between subjects who drank coffee 1224 hours and subjects who drank coffee more than 24 hours prior Comparison between group 1, 2 and 3 doi:10.1371/journal.pone.0130487.t001 coffee drinkers, subjects who drank coffee 1224 hours prior and those who drank coffee more than 24 hours to stress testing. SBP change, HR change and %MPHR were significantly higher in non-coffee drinkers compared to those who drank coffee 1224 hours prior. %Change HR was not significantly different between group 1 and 2. There was no significant difference in SBP change, HR change, %MPHR, and %Change HR between non-coffee drinkers and those who drank coffee >24 hours prior. Moreover, subjects who drank coffee >24 hours prior exhibited higher SBP change and HR change as compared to those who drank coffee 1224 hours prior to testing. MPHR and %Change HR were higher among group 3 compared to group 2 but failed to achieve statistical significance . After adjusting for age, race, weight, Scutellarein web chocolate consumption, diuretics use, history of coronary artery disease, past myocardial infarction, asthma, calcium channel blocker and beta blocker use, Change SBP, Change in HR and %MPHR remained significantly different between non-coffee drinkers and subjects who consumed coffee 1224 hours prior in multivariable regression analysis. Moreover, on multivariable regression analysis, Change SBP, Change HR, and % Change HR remained significantly different between subjects who drank coffee 12 24 hours and subjects who drank coffee more than 24 hours prior. Among subjects who drank coffee 1224 hours prior to regadenoson administration, the number of coffee drinks did not have any effect on Change PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19734877 HR, PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19735646 Change SBP, MPHR and %Change HR. The number of self-reported adverse effects was lower in subjects exposed to caffeine 12 24 hours prior to regadenoson, as compared to >24 hours prior. Group 2 developed less abdominal pain, nausea and dizziness when compared to groups 1 and 3. HR: heart rate. SBP: systolic blood pressure. DBP: diastolic bloo