Table 7.
Currents during the 520 mV sec−1 ramp in VM and P cells
| n 17, Param | VM cells | P cells | Δ (mV or %) |
|---|---|---|---|
| Vh (mV) | −80.6 ± 0.5 | −81.8 ± 0.9 | −0.7 mV |
| IK1 peak (pA) | 963 ± 108 | 518 ± 57* | +46.2% |
| IK1 peak (mV) | −52.3 ± 0.7 | −58.3 ± 0.7* | 6 mV |
| INS (pA) | −278 ± 36 | −546 ± 48* | −49.0% |
| INS, peak | −18.1 ± 2.6 | −22.4 ± 1.6 | 4.3 mV |
| INa3 (pA) | −1458 ± 170 (17/17) | −1352 ± 175 (14/17) | +7.8% |
| INa1Th (mV) | −39.2 ± 1.2 | −46.8 ± 1.2* | 7.6 mV |
| INa1 (pA) | −8373 ± 553 (17/17) | −9439 ± 352 (14/17) | −11.9% |
| End INa1 (pA) | 837 ± 113 | 381 ± 69* | +119.6% |
| End INa1 (mV) | −32.6 ± 1.2 | −38.5 ± 1.0* | 5.9 mV |
| ICa, start (mV) | −4.9 ± 1.9 | −11.5 ± 0.5* | 6.6 mV |
| ICa (pA) | −119.2 ± 31.7 (16/17) | −16.4 ± 14.1* (2/17) | +626.8% |
| ICa peak (mV) | 17.4 ± 0.9 | −3.5 ± 7.5 | 20.9 mV |
| Ito, start (mV) | 10.3 ± 3.4 | −17.1 ± 2.0* (17/17) | 27.4 mV |
| Ito (pA) | 223 ± 27.0 | 1478 ± 173* (17/17) | −84.9% |
| Iramp peak−Ih (pA) | 823 ± 88 | 1405 ± 167 | −41.4% |
| Irepol (pA) | 198 ± 32 | 1169 ± 144* | −83.0% |
| Irepol peak (mV) | 3.1 ± 3.6 | −16.6 ± 2.0* | 19.4 mV |
| IPS, start (mV) | 0.2 ± 3.7 | −17.1 ± 1.8* | 17.3 mV |
| IPS (pA) | 219 ± 34 | 122 ± 20 | 79.5% |
| IPS peak (mV) | −45.3 ± 1.7 | −49.8 ± 1.0* | 4.5 mV |
| IPS peak−Ih (pA) | 850 ± 105 | 349 ± 55* | +143.5% |
n, number of cells studied; Δ (mV or%), difference in mV or percent of VM cells data with respect to P cells data; IK1 peak (pA), amplitude of IK1 peak in pA, measured as the difference from Ih; IK1 peak (mV), voltage in mV at which IK1 peaked; INS (pA), current amplitude in pA during the negative slope region; INS, peak (mV), voltage in mV of INS peak; INa1 Th (mV), voltage at which INa1 began; INa1 (pA), amplitude in pA of INa1; ICa start (mV), beginning of ICa component in mV determined as the departure of current trace from INS peak; ICa (pA), amplitude of ICa component in pA as the difference between its beginning and its peak; ICa peak (mV), peak in mV of ICa; Ito, start (mV), voltage in mV at which the increasing outward current started at INS or ICa peaks; Ito (pA), amplitude of outward current in pA measured between its beginning and ramp peak; Iramp peak−Ih (pA), outward current at ramp peak measured as difference from Ih; Irepol (pA), amplitude in pA of the outward current between ramp peak and its smallest value prior to the beginning of IPS; Irepol peak (mV), voltage in mV at which the outward current was smallest prior to INS beginning; IPS start (mV), voltage in mV at which IPS began; IPS (pA), current in pA at IPS peak, measured as difference between its beginning and its peak; IPS peak (mV), voltage in mV at which PS region peaked; IPS peak−Ih (pA), current in pA measured as difference between INS peak and Ih; End INa1 (pA), amplitude in pA of the current at the end of INa1 inactivation; End INa1 (mV), voltage in mV of the current at the end of INa1 inactivation; Vh (mV), holding potential in mV; Param, parameters measured; VM cells, data from ventricular myocardial cells; P cells, data from Purkinje cells; INa3 (pA), amplitude in pA of INa3 measured as the difference between its peak and the end of the step; Numbers in parenthesis (e.g., 17/17), number of cells with the parameter present over the total number of cells studied; *statistically significant difference between P and VM cells data.