Abstract
Studies of the effect of nitric oxide (NO) synthesis inhibition were performed in the isometrically contracting blood-perfused canine gastrocnemius-plantaris muscle group. Muscle blood flow (Q) was controlled with a pump during continuous NO blockade produced with either 1 mM L- argininosuccinic acid (L-ArgSA) or N(G)-nitro-L-arginine methyl ester (L- NAME) during repetitive tetanic contractions (50-Hz trains, 200-ms duration, 1/s). Pump Q was set to match maximal spontaneous Q (1.3-1.4 ml·min- 1·g-1) measured in prior, brief (3-5 min) control contraction trials in each muscle. Active tension and oxygen uptake were 500-600 g/g and 200-230 μl·min-1·g-1, respectively, under these conditions. Within 3 min of L- ArgSA infusion, vascular resistance across the muscle (R(v)) increased significantly (from ~100 to 300 peripheral resistance units; P < 0.05), whereas R(v) increased to a lesser extent with L-NAME (from ~100 to 175 peripheral resistance units; P < 0.05): The increase in R(v) with L-ArgSA was unchanged by simultaneous infusion of 0.5-10 mM L-arginine but was reduced with 1-3 μg/ml sodium nitroprusside (41-54%). The increase in R(v) with L- NAME was reversed with 1 mM of L-arginine. Increased fatigue occurred with infusion of L-ArgSA; active tension and intramuscular pressure decreased by 62 and 66%, whereas passive tension and baseline intramuscular pressure increased by 80 and 30%, respectively. These data indicate a possible role for NO in the control of R(v) and contractility within the canine gastrocnemius-plantaris muscle during repetitive tetanic contractions.
Original language | English (US) |
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Pages (from-to) | 142-151 |
Number of pages | 10 |
Journal | Journal of Applied Physiology |
Volume | 87 |
Issue number | 1 |
DOIs | |
State | Published - Jul 1999 |
Externally published | Yes |
Keywords
- Canine
- Endothelium-derived relaxation factor
- Fatigue
- Gastrocnemius muscle
- Hyperemia
- Intramuscular pressure
- Passive tension
ASJC Scopus subject areas
- General Medicine