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. 1993 Dec;472:23–31. doi: 10.1113/jphysiol.1993.sp019933

Occurrence of intracellular pH transients during spontaneous contractions in rat uterine smooth muscle.

M J Taggart 1, S Wray 1
PMCID: PMC1160473  PMID: 8145141

Abstract

1. Intracellular pH (pHi) and contraction have been measured simultaneously in isolated longitudinal rat myometrium. Tissue was loaded with the pH-sensitive fluorophore carboxy-SNARF and superfused with oxygenated, buffered salt solution at 37 degrees C and pH 7.4. 2. Small (0.04 pH unit) transient intracellular acidifications followed each spontaneous uterine contraction. The pHi transients lagged contraction by 15 s. Removal of external Ca2+ abolished both spontaneous contractions and the pHi changes. 3. Increasing uterine contraction by depolarization (40 mM K+) or agonist (50 microM carbachol) produced a larger acidification (0.18 pH unit). 4. The acidification with contraction does not appear to be due to increased glycolysis as no increase in lactate efflux occurred with high-K+ stimulation. 5. Uterine contraction is known to be sensitive to changes in pHi. Comparable pHi changes to the pHi transients seen during spontaneous contraction were induced by application and withdrawal of weak acids and bases. The resulting pHi changes (0.02-0.08 pH unit) produced effects on contraction frequency and amplitude, alkalinization augmenting and acidification depressing contractile activity, suggesting that the pHi transients with contraction are functionally important.

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Selected References

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  1. Aalkjaer C., Cragoe E. J., Jr Intracellular pH regulation in resting and contracting segments of rat mesenteric resistance vessels. J Physiol. 1988 Aug;402:391–410. doi: 10.1113/jphysiol.1988.sp017211. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Austin C., Wray S. Extracellular pH signals affect rat vascular tone by rapid transduction into intracellular pH changes. J Physiol. 1993 Jul;466:1–8. [PMC free article] [PubMed] [Google Scholar]
  3. Batlle D. C., Peces R., LaPointe M. S., Ye M., Daugirdas J. T. Cytosolic free calcium regulation in response to acute changes in intracellular pH in vascular smooth muscle. Am J Physiol. 1993 Apr;264(4 Pt 1):C932–C943. doi: 10.1152/ajpcell.1993.264.4.C932. [DOI] [PubMed] [Google Scholar]
  4. Buckler K. J., Vaughan-Jones R. D. Application of a new pH-sensitive fluoroprobe (carboxy-SNARF-1) for intracellular pH measurement in small, isolated cells. Pflugers Arch. 1990 Oct;417(2):234–239. doi: 10.1007/BF00370705. [DOI] [PubMed] [Google Scholar]
  5. Carafoli E. Intracellular calcium homeostasis. Annu Rev Biochem. 1987;56:395–433. doi: 10.1146/annurev.bi.56.070187.002143. [DOI] [PubMed] [Google Scholar]
  6. Dawson M. J., Wray S. The effects of pregnancy and parturition on phosphorus metabolites in rat uterus studied by 31P nuclear magnetic resonance. J Physiol. 1985 Nov;368:19–31. doi: 10.1113/jphysiol.1985.sp015844. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Eiesland J., Baro I., Raimbach S., Eisner D. A., Wray S. Intracellular pH and buffering power measured in isolated single cells from pregnant rat uterus. Exp Physiol. 1991 Sep;76(5):815–818. doi: 10.1113/expphysiol.1991.sp003548. [DOI] [PubMed] [Google Scholar]
  8. Gevers W. Generation of protons by metabolic processes in heart cells. J Mol Cell Cardiol. 1977 Nov;9(11):867–874. doi: 10.1016/s0022-2828(77)80008-4. [DOI] [PubMed] [Google Scholar]
  9. Himpens B., Somlyo A. P. Free-calcium and force transients during depolarization and pharmacomechanical coupling in guinea-pig smooth muscle. J Physiol. 1988 Jan;395:507–530. doi: 10.1113/jphysiol.1988.sp016932. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Kroeger E. A. Effect of ionic environment on oxygen uptake and lactate production of myometrium. Am J Physiol. 1976 Jan;230(1):158–162. doi: 10.1152/ajplegacy.1976.230.1.158. [DOI] [PubMed] [Google Scholar]
  11. Motley E. D., Paul R. J., Matlib M. A. Role of Na(+)-Ca2+ exchange in the regulation of vascular smooth muscle tension. Am J Physiol. 1993 Apr;264(4 Pt 2):H1028–H1040. doi: 10.1152/ajpheart.1993.264.4.H1028. [DOI] [PubMed] [Google Scholar]
  12. Taggart M., Wray S. Simultaneous measurement of intracellular pH and contraction in uterine smooth muscle. Pflugers Arch. 1993 Jun;423(5-6):527–529. doi: 10.1007/BF00374951. [DOI] [PubMed] [Google Scholar]
  13. Wray S., Duggins K., Iles R., Nyman L., Osman V. The effects of metabolic inhibition and acidification on force production in the rat uterus. Exp Physiol. 1992 Mar;77(2):307–319. doi: 10.1113/expphysiol.1992.sp003590. [DOI] [PubMed] [Google Scholar]
  14. Wray S. Smooth muscle intracellular pH: measurement, regulation, and function. Am J Physiol. 1988 Feb;254(2 Pt 1):C213–C225. doi: 10.1152/ajpcell.1988.254.2.C213. [DOI] [PubMed] [Google Scholar]
  15. Wray S. The effects of metabolic inhibition on uterine metabolism and intracellular pH in the rat. J Physiol. 1990 Apr;423:411–423. doi: 10.1113/jphysiol.1990.sp018030. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Wray S. Uterine contraction and physiological mechanisms of modulation. Am J Physiol. 1993 Jan;264(1 Pt 1):C1–18. doi: 10.1152/ajpcell.1993.264.1.C1. [DOI] [PubMed] [Google Scholar]
  17. Yu J., Zheng J. J., Ong B. Y., Bose R. Intracellular pH measurement with fluorescent dye in canine basilar arteries. Blood Vessels. 1991;28(6):464–474. doi: 10.1159/000158893. [DOI] [PubMed] [Google Scholar]

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