ROLE OF DIPROTONATED PHOSPHATE IN EVOKING MUSCLE-REFLEX RESPONSES IN CATS AND HUMANS
Sinoway, LI; Smith, MB; Enders, B; Leuenberger, U; Dzwonczyk, T; Gray, K; Whisler, S; Moore, RL
| HERO ID | 5182090 |
|---|---|
| In Press | No |
| Year | 1994 |
| Title | ROLE OF DIPROTONATED PHOSPHATE IN EVOKING MUSCLE-REFLEX RESPONSES IN CATS AND HUMANS |
| Authors | Sinoway, LI; Smith, MB; Enders, B; Leuenberger, U; Dzwonczyk, T; Gray, K; Whisler, S; Moore, RL |
| Journal | American Journal of Physiology |
| Volume | 267 |
| Issue | 2 |
| Page Numbers | H770-H778 |
| Abstract | Lactic acid and H+ evoke muscle reflexes that raise sympathetic nerve activity. Whether these substances are direct afferent stimulants or markers for the acidification of other substances is unknown. Diprotonated phosphate (H2PO4-), a possible mediator of fatigue, increases as the cell acidifies and phosphate is produced. Its role in evoking muscle reflexes is unknown. We used 31P-nuclear magnetic resonance to measure forearm muscle H+ and H2PO4- and microneurography to measure muscle sympathetic nerve activity (MSNA, peroneal nerve) during a handgrip protocol designed to dissociate H+ from H2PO4-. Ischemic handgrip (50% maximal voluntary contraction x 2 min) was followed by a 1-min rest period during which the muscle was freely perfused. This was followed by a second bout of ischemic handgrip and a 5-min recovery. In seven of eight subjects, MSNA correlated with H2PO4-, whereas it correlated with pH in only one subject. To determine whether muscle reflex responses are evoked by H+, lactic acid, monoprotonated phosphate (HPO4(2-), or H2PO4-, we injected H+, lactate, H2PO4- [all 50 mM in 10 mM N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) buffered to pH 6], and HPO4(2-) (50 mM, pH 7.5 in 10 mM HEPES) into the arterial supply of the triceps surae of the cat (n = 9) as we measured mean arterial blood pressure (MAP). H2PO4- increased MAP more than HPO4(2-), H+, or lactate (27.1 +/- 3.7 vs. 5.0 +/- 1.3, 4.6 +/- 3.1, and 7.7 +/- 3.2 rise in mmHg).(ABSTRACT TRUNCATED AT 250 WORDS) |
| Doi | 10.1152/ajpheart.1994.267.2.H770 |
| Pmid | 8067433 |
| Wosid | WOS:A1994PC44100046 |
| Is Certified Translation | No |
| Dupe Override | No |
| Is Public | Yes |
| Language Text | English |
| Keyword | EXERCISE; SYMPATHETIC NERVOUS SYSTEM; NUCLEAR MAGNETIC RESONANCE; MICRONEUROGRAPHY |