Opposing effects of α1-adrenergic receptor subtypes on Ca2+ and pH homeostasis in rat cardiac myocytes

Giovanni Gambassi, Harold A. Spurgeon, Bruce D. Ziman, Edward G. Lakatta, Maurizio C. Capogrossi

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

We examined the effect of α1-adrenergic receptor (AR) subtypes on contraction, cytosolic Ca2+ concentration ([Ca2+](i)), and cytosolic pH (pH(i)) of rat ventricular myocytes loaded with the Ca2+ indicator indo 1 or the pH indicator carboxyseminaphthorhodafluor-1. Nonselective α1-AR stimulation was effected with phenylephrine plus nadolol. α1-AR subtype stimulation was achieved with α1-AR and chloroethylclonidine (CEC) or with α1-AR and WB-4101. Cells were in bicarbonate buffer with 0.5 mM Ca2+ and were electrically stimulated at 0.5 Hz. Results show that 1) nonselective α1-AR stimulation increased twitch and [Ca2+](i) transient amplitudes, myofilament response to Ca2+ via cytosolic alkalinization; 3) α1-AR plus WB-4101 decreased twitch and [Ca2+](i) transient amplitudes and also pH(i); and 4) cytosolic acidification due to α1-AR plus WB-4101 was abolished by protein kinase C inhibition (staurosporine pretreatment) or downregulation (prolonged exposure to phorbol esters). In summary, the net effects of α1- adrenergic stimulation on contraction, [Ca2+](i) and pH(i) are due to opposing WB-4101- and CEC-sensitive α1-AR subtype signaling pathways.

Original languageEnglish
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume274
Issue number4 43-4
Publication statusPublished - Apr 1998

Fingerprint

Cardiac Myocytes
Adrenergic Receptors
Homeostasis
Nadolol
Staurosporine
Myofibrils
Phorbol Esters
Phenylephrine
Bicarbonates
Adrenergic Agents
Muscle Cells
Protein Kinase C
Buffers
Down-Regulation
(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane

Keywords

  • α-adrenoceptor subtypes
  • Cardiac inotropy
  • Chloroethylclonidine
  • Cytosolic pH
  • Indo 1
  • WB-4101

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

Opposing effects of α1-adrenergic receptor subtypes on Ca2+ and pH homeostasis in rat cardiac myocytes. / Gambassi, Giovanni; Spurgeon, Harold A.; Ziman, Bruce D.; Lakatta, Edward G.; Capogrossi, Maurizio C.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 274, No. 4 43-4, 04.1998.

Research output: Contribution to journalArticle

Gambassi, Giovanni ; Spurgeon, Harold A. ; Ziman, Bruce D. ; Lakatta, Edward G. ; Capogrossi, Maurizio C. / Opposing effects of α1-adrenergic receptor subtypes on Ca2+ and pH homeostasis in rat cardiac myocytes. In: American Journal of Physiology - Heart and Circulatory Physiology. 1998 ; Vol. 274, No. 4 43-4.
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