Skip to main content
NCBI home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1972 Jul;224(1):35–59. doi: 10.1113/jphysiol.1972.sp009880

Ca concentration and flux in Ca-deprived arteries

W R Keatinge
PMCID: PMC1331525  PMID: 4625125

Abstract

1. Extracellular Ca and EDTA concentrations in arterial smooth muscle in Ca-free solutions with and without EDTA were estimated from 45Ca and [14C]EDTA washout studies. Ca concentrations were calculated from the measured rate of 45Ca washout at a given moment, combined with separate determinations of the coefficient of diffusion of Ca in the tissue, while EDTA concentrations were calculated by analysing an exponential phase of [14C]EDTA washout and checked by separate determinations of coefficient of diffusion of EDTA in the tissue.

2. Extracellular Ca concentrations after 30 min in simple Ca-free saline at 36° C was 0·049 mM at the centre of the tissue and averaged 0·033 mM throughout the tissue; these were well above the value of 0·005 mM-Ca that was found to be the threshold external level for contraction after tissue stores of Ca were removed.

3. Extracellular EDTA concentration at the centre of the tissue reached 6·25 mM after 1·9 min in EDTA 12·5 mM at 36° C or after 4·9 min at 5° C. It reached 12·45 mM after 30 min at 5° C, enough to keep free extracellular Ca at this point well below threshold even if all of the Ca in the tissue, determined as 0·42 μmole/g, were suddenly released on warming.

4. Ca efflux increased greatly on warming after long periods in cold EDTA, and all measurable Ca left the tissue within 30 min in EDTA 12·5 mM at 36° C although tissue Mg did not fall significantly during this time.

5. Contractions elicited by noradrenaline in Ca-free saline, with or without EDTA present, were not associated with any increases in the rate of external loss of Ca greater than 0·001 μmole.g-1.min-1.

6. Electronmicrographs showed numerous microvesicles that communicated with the extracellular space; also smooth endoplasmic reticulum among other structures that might have contained non-communicating Ca stores.

7. The results provide evidence that large responses given by the arteries to noradrenaline in simple Ca-free saline were due to persisting extracellular Ca or to labile Ca stores dependent on this, while small responses obtained after long periods in cold EDTA depended on non-communicating Ca stores whose loss was too temperature-dependent to be limited by diffusion.

Full text

PDF
35

Images in this article

58-2A
on p.58-2
58-2B
on p.58-2

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ashley C. C. An estimate of calcium concentration changes during the contraction of single muscle fibres. J Physiol. 1970 Sep;210(2):133P–134P. [PubMed] [Google Scholar]
  2. Carsten M. E. Role of calcium binding by sarcoplasmic reticulum in the contraction and relaxation of uterine smooth muscle. J Gen Physiol. 1969 Apr;53(4):414–426. doi: 10.1085/jgp.53.4.414. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. FILO R. S., BOHR D. F., RUEGG J. C. GLYCERINATED SKELETAL AND SMOOTH MUSCLE: CALCIUM AND MAGNESIUM DEPENDENCE. Science. 1965 Mar 26;147(3665):1581–1583. doi: 10.1126/science.147.3665.1581. [DOI] [PubMed] [Google Scholar]
  4. Gabella G. Caveolae intracellulares and sarcoplasmic reticulum in smooth muscle. J Cell Sci. 1971 May;8(3):601–609. doi: 10.1242/jcs.8.3.601. [DOI] [PubMed] [Google Scholar]
  5. Hagiwara S., Nakajima S. Effects of the intracellular Ca ion concentration upon the excitability of the muscle fiber membrane of a barnacle. J Gen Physiol. 1966 Mar;49(4):807–818. doi: 10.1085/jgp.49.4.807. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Hamoir G. The muscle proteins of the vascular wall. Angiologica. 1969;6(2):190–225. doi: 10.1159/000157789. [DOI] [PubMed] [Google Scholar]
  7. Hellam D. C., Podolsky R. J. Force measurements in skinned muscle fibres. J Physiol. 1969 Feb;200(3):807–819. doi: 10.1113/jphysiol.1969.sp008723. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Herz R., Weber A., Reiss I. The role of magnesium in the relaxation of myofibrils. Biochemistry. 1969 Jun;8(6):2266–2271. doi: 10.1021/bi00834a005. [DOI] [PubMed] [Google Scholar]
  9. Hudgins P. M. Some drug effects on calcium movements in aortic strips. J Pharmacol Exp Ther. 1969 Dec;170(2):303–310. [PubMed] [Google Scholar]
  10. KEYNES R. D. The ionic fluxes in frog muscle. Proc R Soc Lond B Biol Sci. 1954 May 27;142(908):359–382. doi: 10.1098/rspb.1954.0030. [DOI] [PubMed] [Google Scholar]
  11. Keatinge W. R. Mechanical response with reversed electrical response to noradrenaline by Ca-deprived arterial smooth muscle. J Physiol. 1972 Jul;224(1):21–34. doi: 10.1113/jphysiol.1972.sp009879. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Keatinge W. R. Sodium flux and electrical activity of arterial smooth muscle. J Physiol. 1968 Jan;194(1):183–200. doi: 10.1113/jphysiol.1968.sp008401. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. PORTZEHL H., CALDWELL P. C., RUEEGG J. C. THE DEPENDENCE OF CONTRACTION AND RELAXATION OF MUSCLE FIBRES FROM THE CRAB MAIA SQUINADO ON THE INTERNAL CONCENTRATION OF FREE CALCIUM IONS. Biochim Biophys Acta. 1964 May 25;79:581–591. doi: 10.1016/0926-6577(64)90224-4. [DOI] [PubMed] [Google Scholar]
  14. Reuben J. P., Brandt P. W., Berman M., Grundfest H. Regulation of tension in the skinned crayfish muscle fiber. I. Contraction and relaxation in the absence of Ca (pCa is greater than 9). J Gen Physiol. 1971 Apr;57(4):385–407. doi: 10.1085/jgp.57.4.385. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Schirmer R. H. Die Besonderheiten des contractilen Proteins der Arterien. Biochem Z. 1965 Dec 1;343(3):269–282. [PubMed] [Google Scholar]
  16. Seidel C. L., Bohr D. F. Calcium and vascular smooth muscle contraction. Circ Res. 1971 May;28(5 Suppl):88–95. doi: 10.1161/01.res.28.5.ii-88. [DOI] [PubMed] [Google Scholar]
  17. Sparrow M. P., Maxwell L. C., Ruegg J. C., Bohr D. F. Preparation and properties of a calcium ion-sensitive actomyosin from arteries. Am J Physiol. 1970 Nov;219(5):1366–1372. doi: 10.1152/ajplegacy.1970.219.5.1366. [DOI] [PubMed] [Google Scholar]
  18. Weber A. Parallel response of myofibrillar contraction and relaxation to four different nucleoside triphophates. J Gen Physiol. 1969 Jun;53(6):781–791. doi: 10.1085/jgp.53.6.781. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES