Article Figures & Data
Figures
- FIGURE 1.
Imaging protocol. (A) Acquisition protocol for each of the 4 PET/CT imaging sessions. Both rest and stress scans were acquired over 6 min. (B) Study protocol for the 40 healthy volunteers. CTAC = computed tomographic attenuation correction.
- FIGURE 2.
Rest MBF obtained in the volunteers sorted by sex and plasma caffeine concentration with and without RPP correction. W = women; M = men; RPP = rate pressure product; N = number of MPI sessions fulfilling the criteria.
- FIGURE 3.
Stress MBF obtained in the volunteers sorted by sex and plasma caffeine concentration, with and without RPP correction. W = women; M = men; RPP = rate pressure product; N = number of MPI sessions fulfilling the criteria.
- FIGURE 4.
Relationship between ingested caffeine (mg) and the corresponding plasma caffeine concentrations (mg/L). The plasma caffeine concentrations obtained at 75 and 90 min are given as mean ± SEM in both men (closed blue triangles, n = 9–20) and women (closed red circles, n = 9–18).
- FIGURE 5.
Relationship between average plasma concentration of caffeine [mg/L] (log) and stress MBF. Points represent mean values, and vertical lines indicate SEM. MBF values were normalized to the maximum stress MBF obtained for the individual volunteers (men, closed blue triangles, n = 9–20, and women, closed red circles, n = 9–18, respectively).
- FIGURE 6.
MFR obtained in the volunteers sorted by sex and plasma caffeine levels. W = women; M = men; RPP = rate pressure product; N = number of MPI sessions fulfilling the criteria.
Tables
- TABLE 1.
Heart Rate (Beats per Minute) Obtained During Scans Using 4 Levels of Plasma Caffeine Concentration
Plasma caffeine concentration (mg/L) PCC ≤1 1 < x ≤ 3 3 < x ≤ 5 >5 Rest Women 62.4 ± 10.8 (31) 51.4 ± 7.3* (31) 68.0 ± 14.3 (6) 60.9 ± 10.6 (29) Men 60.2 ± 13.0 (38) 53.8 ± 12.1 (12) 55.7 ± 9.0† (14) 60.1 ± 9.3 (14) Stress Women 92.5 ± 14.4 79.3 ± 23.6* 91.5 ± 9.7 78.2 ± 15.2* Men 80.9 ± 19.7† 73.3 ± 18.8 74.4 ± 15.8† 70.6 ± 13.2 * Significant variations in the heart rate between the baseline scans (plasma caffeine concentration < 1 mg/L) and studies with increased plasma caffeine concentrations.
↵†Intersex differences in the heart rate observed for the respective plasma caffeine concentrations.
Numbers given in parentheses for the rest scans indicate the number of MPI sessions fulfilling the criteria. Differences were considered significant for P < 0.05.
PCC = plasma caffeine concentration.
- TABLE 2.
Test–Retest Repeatability (Measured as Coefficient of Variation) for Baseline MPI Sessions (0 mg of Caffeine Ingested)
Coefficient of variation Rest Stress MFR Women (n = 19) 13.5% 10.6% 12.9% Men (n = 20) 16.1% 18.4% 20.6% Combined (n = 39) 15.8% 15.3% 17.8% No differences in test–retest repeatability was observed between the 2 sexes.
- TABLE 3.
Diastolic Blood Pressure Obtained During Scans Using 4 Levels of Plasma Caffeine Concentration
Plasma caffeine concentration (mg/L) PCC ≤1 1 < x ≤ 3 3 < x ≤ 5 >5 Rest Women 60.9 ± 6.5 (31) 62.3 ± 4.6 (8) 60.5 ± 8.3 (6) 64.2 ± 6.4 (29) Men 57.9 ± 9.1 (38) 61.2 ± 7.3 (12) 60.4 ± 5.7 (14) 62.2 ± 5.7 (14) Stress Women 60.8 ± 9.0 68.4 ± 10.2 60.4 ± 5.7 66.3 ± 8.8* Men 54.7 ± 9.0† 61.0 ± 9.8* 58.7 ± 8.1 59.5 ± 6.8† * Significant variations in the diastolic blood pressure between the baseline scans (plasma caffeine concentration < 1 mg/L) and studies with increased plasma caffeine concentrations.
↵†Intersex differences in the diastolic blood pressure observed for the respective plasma caffeine concentrations.
Numbers given in parentheses for the rest scans indicate the number of MPI sessions fulfilling the criteria. Differences were considered significant for P < 0.05.
PCC = plasma caffeine concentration.
- TABLE 4.
Systolic Blood Pressure Obtained During Scans Using 4 Plasma Caffeine Concentration
Plasma caffeine concentration (mg/L) PCC ≤1 1 < x ≤ 3 3 < x ≤ 5 >5 Rest Women 102.6 ± 9.9 (31) 103.9 ± 8.1 (8) 99.2 ± 17.3 (6) 108.7 ± 13.6 (29) Men 108.9 ± 10.7 (38) 112.6 ± 10.0 (12) 112.5 ± 10.7 (14) 114.9 ± 9.3 (14) Stress Women 92.5 ± 14.4 96.5 ± 17.7 102.3 ± 6.4 105.9 ± 12.3 Men 107.0 ± 12.7† 110.6 ± 13.5 112.1 ± 10.1† 111.5 ± 12.1 * Within-sex variations in the systolic blood pressure between the baseline scans (plasma caffeine concentration < 1 mg/L) and studies with increased plasma caffeine concentrations.
↵†Intersex differences in the systolic blood pressure observed for the respective plasma caffeine concentrations.
Numbers given in parentheses for the rest scans indicate the number of MPI sessions fulfilling the criteria. Differences were considered significant for P < 0.05.
PCC = plasma caffeine concentration.
Plasma caffeine concentration (mg/L) PCC ≤1 1 < x ≤ 3 3 < x ≤ 5 >5 Rest Women 6,422 ± 1,381 (31) 5,329 ± 797* (8) 6,626 ± 1,253 (6) 6,627 ± 1,475 (29) Men 6,504 ± 1,381 (38) 6,100 ± 1,739 (12) 6,429 ± 1,075 (14) 6,786 ± 1,447 (14) Stress Women 9,624 ± 2,013 7,480 ± 2,093* 9,328 ± 702 8,333 ± 2,105* Men 8,742 ± 2,350 8,208 ± 2,757 8,279 ± 1,666 7,770 ± 1,703 * Sex-specific differences between the baseline scan (0 mg) and the respective plasma caffeine concentrations.
Numbers given in parentheses for the rest scans indicate the number of MPI sessions fulfilling the criteria. Differences were considered significant for P < 0.05.
PCC = plasma caffeine concentration.
Plasma caffeine concentration (mg/L) PCC ≤1 1 < x ≤ 3 3 < x ≤ 5 >5 Rest Women 82.9 ± 19.4 (31) 85.7 ± 16.8 (8) 77.0 ± 18.5 (6) 92.6 ± 21.1 (29) Men 105.5 ± 30.7* (38) 101.3 ± 26.5 (12) 102.1 ± 27.6 (14) 152.9 ± 25.9*† (14) Stress Women 25.8 ± 5.9 23.0 ± 7.2 21.8 ± 1.4 23.6 ± 8.8 Men 27.5 ± 8.2 33.0 ± 15.2 45.2 ± 25.6*† 51.8 ± 14.8*† * Significant differences for men and women.
†Sex-specific differences between the baseline scan (0 mg) and the respective plasma caffeine concentrations.
Numbers given in parentheses for the rest scans indicate the number of MPI sessions fulfilling the criteria. Differences were considered significant for P < 0.05.
PCC = plasma caffeine concentration.
