Table 2.
A. | Wild-type | nNOS+/− | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
−EX | +EX | −EX | +EX | |||||||||
Con | Ad.eGFP | Ad.nNOS | Con | Ad.eGFP | Ad.nNOS | Con | Ad.eGFP | Ad.nNOS | Con | Ad.eGFP | Ad.nNOS | |
Control | ||||||||||||
3 Hz | 50 | 44 | 123 | 99 | 76 | 126 | 58 | 60 | 139 | 48 | 55 | 137 |
± 5 | ± 4 | ± 12* | ± 11** | ± 3** | ± 8* | ± 8 | ± 10 | ± 36* | ± 8 | ± 3 | ± 10* | |
5 Hz | 89 | 82 | 159 | 112 | 125 | 192 | 86 | 92 | 153 | 85 | 92 | 202 |
± 6 | ± 5 | ± 20* | ± 11** | ± 8** | ± 13* | ± 7 | ± 10 | ± 35* | ± 16 | ± 3 | ± 12* | |
l-VNIO | ||||||||||||
3 Hz | 44 | 31 | 59 | 53 | 51 | 59 | 51 | 40 | 40 | 39 | 50 | 57 |
± 5** | ± 8** | ± 9** | ± 17** | ± 4** | ± 8** | ± 7** | ± 5** | ± 10** | ± 7** | ± 6** | ± 5** | |
5 Hz | 66 | 53 | 78 | 67 | 81 | 86 | 78 | 84 | 75 | 70 | 76 | 91 |
± 12** | ± 17** | ± 17** | ± 10** | ± 4** | ± 7** | ± 4** | ± 11** | ± 23** | ± 13** | ± 5** | ± 7** | |
l-Arg | ||||||||||||
3 Hz | 48 | 62 | 107 | 96 | 82 | 98 | 55 | 59 | 108 | 53 | 58 | 96 |
± 3 | ± 11 | ± 5* | ± 13** | ± 11** | ± 6* | ± 4 | ± 6 | ± 24* | ± 10** | ± 5 | ± 17* | |
5 Hz | 83 | 103 | 140 | 103 | 107 | 132 | 83 | 98 | 116 | 80 | 89 | 147 |
± 5 | ± 10 | ± 40* | ± 8** | ± 11** | ± 11* | ± 7 | ± 8 | ± 20* | ± 12** | ± 4 | ± 22* | |
Baseline HR (beats min−1) | ||||||||||||
376 | 371 | 378 | 350 | 349 | 367 | 383 | 398 | 388 | 354 | 379 | 347 | |
± 25 | ± 18 | ± 29 | ± 19 | ± 33 | ± 30 | ± 20 | ± 29 | ± 25 | ± 23 | ± 34 | ± 32 | |
B. | Wild-type | nNOS+/− | ||||||||||
−EX | +EX | −EX | +EX | |||||||||
Con | Ad.eGFP | Ad.nNOS | Con | Ad.eGFP | Ad.nNOS | Con | Ad.eGFP | Ad.nNOS | Con | Ad.eGFP | Ad.nNOS | |
Control | ||||||||||||
3 Hz | 34 | 31 | 87 | 69 | 49 | 99 | 28 | 29 | 89 | 27 | 32 | 108 |
± 2 | ± 1 | ± 5* | ± 7** | ± 3** | ± 5* | ± 3 | ± 4 | ± 16* | ± 4 | ± 2 | ± 5* | |
5 Hz | 59 | 54 | 127 | 82 | 97 | 210 | 45 | 49 | 104 | 54 | 60 | 226 |
± 2 | ± 2 | ± 9* | ± 7** | ± 5** | ± 8* | ± 3 | ± 4 | ± 15* | ± 9 | ± 2 | ± 6* | |
l-VNIO | ||||||||||||
3 Hz | 31 | 24 | 39 | 32 | 31 | 36 | 24 | 18 | 18 | 21 | 28 | 33 |
± 12 | ± 13 | ± 13† | ± 10† | ± 3† | ± 5† | ± 3 | ± 2† | ± 4† | ± 4† | ± 3† | ± 3† | |
5 Hz | 44 | 36 | 51 | 42 | 53 | 57 | 40 | 44 | 38 | 42 | 47 | 59 |
± 15 | ± 17 | ± 17† | ± 6† | ± 3† | ± 5† | ± 1† | ± 4 | ± 10† | ± 7† | ± 3† | ± 4† | |
l-Arg | ||||||||||||
3 Hz | 32 | 41 | 73 | 66 | 54 | 68 | 26 | 28 | 61 | 30 | 34 | 64 |
± 1 | ± 4 | ± 2* | ± 8** | ± 7** | ± 4* | ± 1 | ± 2 | ± 10* | ± 5† | ± 3 | ± 9* | |
5 Hz | 55 | 70 | 104 | 73 | 77 | 105 | 43 | 54 | 68 | 50 | 57 | 121 |
± 2 | ± 4 | ± 2* | ± 5** | ± 7** | ± 7* | ± 3 | ± 3 | ± 8* | ± 6† | ± 2 | ± 12* |
In vitro atrial beating rate responses to vagal nerve stimulation (VNS) at 3 and 5 Hz stimulation frequencies. Part A shows rate responses calculated as beats per minute change and part B shows responses expressed as change in contraction interval (ms). Control responses were significantly increased in trained (+EX) compared to untrained (−EX) in wild-type tissue
P < 0.05, unpaired t test), although this effect was not present in atria from mice lacking one allele of neuronal nitric oxide synthase (nNOS+/−). Gene transfer using adenoviruses containing nNOS (Ad.nNOS) increased responses to VNS in all atria compared to gene transfer using adenoviruses containing enhanced green fluorescent protein (Ad.eGFP) and control (Con, no gene transfer) atria
P < 0.01, unpaired t test). Selective nNOS inhibition with vinyl-l-N-5-(1-imino-3-butenyl)-l-ornithine (l-VNIO, 100 µmol l−1) attenuated the response to nerve stimulation in all atria, and abolished the effects of training and Ad.nNOS treatment. This effect was reversed in all cases with l-arginine l-Arg, 1 mmol l−1,
P < 0.05, repeated measures ANOVA.