+ Site Statistics
+ Search Articles
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ PDF Full Text
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Translate
+ Recently Requested

Effect of amiloride on diaphragmatic contractility: evidence of a role for Na(+)-Ca2+ exchange

Effect of amiloride on diaphragmatic contractility: evidence of a role for Na(+)-Ca2+ exchange

Journal of Applied Physiology 70(3): 1309-1314

Extracellular Ca2+ has been shown to be important for the normal function of the diaphragm. In this study we have examined the potential importance of Na(+)-Ca2+ exchange as a mechanism for Ca2+ influx during the contractile process by studying the effect of inhibition or stimulation of Na(+)-Ca2+ exchange. Blockade of Na(+)-Ca2+ exchange with amiloride attenuated the twitch response, altered the force-frequency response curve, and enhanced the development of fatigue. The effect of amiloride could be partially reversed by increasing the extracellular Ca2+ concentration. The ability of amiloride to decrease force was associated with decreased Ca2+ uptake by the diaphragm. Enhancing intracellular Na(+)-extracellular Ca2+ exchange by inhibiting the Na(+)-K+ pump significantly decreased the rate of the development of muscle fatigue (89%). The maximal inhibition of diaphragmatic force produced by the amiloride analogue benzamil, which possesses 10-fold greater selectivity for Na(+)-Ca2+ exchange, was not significantly different from that produced by amiloride (76.2 +/- 1.1%), with a concentration that decreased maximum force by 50% equal to 46 microM compared with 460 microM for amiloride. Both agents slowed the maximal rate of relaxation up to 90%. Benzamil elevated resting tension during continuous stimulation of the diaphragm at 0.15 Hz. The results suggest that Na(+)-Ca2+ exchange may have a role in the normal function of the diaphragm.

(PDF emailed within 0-6 h: $19.90)

Accession: 017870630

Download citation: RISBibTeXText

PMID: 2032997

DOI: 10.1152/jappl.1991.70.3.1309

Related references

Reperfusion arrhythmias evidence for a role for sodium proton exchange and an antiarrhythmic effect of amiloride. Circulation 76(4 PART 2): IV-56, 1987

Role of diaphragmatic blood flow and extracellular calcium in the potentiating effect of aminophylline on diaphragmatic contractility. Federation Proceedings 43(4): ABSTRACT 3591, 1984

Effects of proton buffering and of amiloride derivatives on reperfusion arrhythmias in isolated rat hearts. Possible evidence for an arrhythmogenic role of Na(+)-H+ exchange. Circulation Research 66(4): 1156-1159, 1990

Effects of N-chlorobenzyl analogues of amiloride on myocardial contractility, Na-Ca-exchange carrier and other cardiac enzymatic activities. Naunyn-Schmiedeberg's Archives of Pharmacology 336(6): 661-669, 1987

Amiloride, but not DIDS and NPPB, inhibit secretion -induced choleresis Evidence for a role of Na+/H+, but not Cl-HCO3- exchange and Cl- channels, in ductular bile formation. Hepatology 22(4 PART 2): 315A, 1995

Influence of cooling on amiloride positive inotropic effect in isolated atria: role of Na+/Ca2+ exchange. Pharmacological Research 25 Suppl 1: 65-66, 1992

Evidence for a role of sodium calcium exchange in the regulation of contractility in chick embryonic myo cardial cell aggregates. Biophysical Journal 33(2 PART 2): 10A, 1981

Influence of cooling on amiloride positive inotropic effect in isolated atria role of sodium calcium exchange. Pharmacological Research 25(SUPPL 1): 65-66, 1992

Amiloride attenuates the negative inotropic effect of phorbol 12 myristate 13 acetate possible role of sodium proton exchange. Circulation 80(4 SUPPL 2): II127, 1989

Amiloride inhibits phorbol ester-stimulated Na+/H+ exchange and protein kinase C. An amiloride analog selectively inhibits Na+/H+ exchange. Journal of Biological Chemistry 260(2): 1155-1159, 1985

The role of the Na+/H+ exchange system in cardiac cells in relation to the control of the internal Na+ concentration. A molecular basis for the antagonistic effect of ouabain and amiloride on the heart. Journal of Biological Chemistry 259(14): 8880-8885, 1984

Apnea in preterm infants role of aminophylline and diaphragmatic contractility. Pediatric Research 25(4 PART 2): 313A, 1989

Diaphragmatic contractility enhanced by aminophylline: role of extracellular calcium. Journal of Applied Physiology: Respiratory, Environmental and Exercise Physiology 54(2): 460-464, 1983

Effect of aminophylline on diaphragmatic contractility. IRCS (International Research Communications System) Medical Science Library Compendium 11(4): 315-316, 1983

The effect of malnutrition on diaphragmatic contractility. Society for Neuroscience Abstracts 10(2): 783, 1984