This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Okumura, K. Articles by Homma, Y. Search for Related Content PubMed PubMed Citation Articles by Okumura, K. Articles by Homma, Y.

CLINICAL STUDY: VARIANT ANGINA

Enhanced phospholipase C activity in the cultured skin fibroblast obtained from patients with coronary spastic angina: possible role for enhanced vasoconstrictor response

Ken Okumura, MD^*, Tomohiro Osanai, MD^*, Takuo Kosugi, MD^*, Hiroyuki Hanada, MD^*, Hiroshi Ishizaka, MD^*, Tomohisa Fukushi, MD^*, Takaatsu Kamada, MD^*, Takeshi Miura, MD^*, Toru Hatayama, MD^*, Takao Nakano, MD^*, Yasuhiro Fujino, MD^* and Yoshimi Homma, PhD

^* Second Department of Internal Medicine, Hirosaki University School of Medicine, Hirosaki, Japan
Department of Biomolecular Science, Fukushima Medical College, Fukushima, Japan

Manuscript received March 3, 2000; revised manuscript received June 12, 2000, accepted July 20, 2000.

Reprint requests and correspondence: Dr. Ken Okumura, Second Department of Internal Medicine, Hirosaki University School of Medicine, Zaifu-cho 5, Hirosaki, 036-8562 Japan.
okumura{at}cc.hirosaki-u.ac.jp

OBJECTIVES

We measured phospholipase C (PLC) activity in the cultured skin fibroblasts obtained from patients with and without coronary spasm and examined its correlation with coronary artery vasomotility.

BACKGROUND

Coronary artery vasomotility is enhanced in coronary spastic angina (CSA), but no information is available for the intracellular signaling. In spontaneously hypertensive rats, PLC activity in the skin fibroblasts has been shown to be enhanced.

METHODS

Skin fibroblasts obtained from 24 patients with CSA—14 with organic coronary artery disease (CAD) and 12 control subjects—were cultured by the explant method. Activity of PLC was determined by incubating the membrane fraction with ³H-phosphatidyl inositol bisphosphate and by quantifying ³H-inositol trisphosphate. In patients with CSA and control subjects, the relations between PLC activity and coronary artery basal tone and constrictor response to intracoronary acetylcholine (ACh) were examined.

RESULTS

Activity of PLC (pmol/protein [mg] per min) was 1.74 ± 0.19 in patients with CSA; 0.90 ± 0.12 in patients with CAD; and 0.65 ± 0.07 in control subjects (p < 0.001, patients with CSA vs. patients with CAD and control subjects; p = NS, patients with CAD vs. control subjects). According to the Lineweaver-Burk plot, Michaelis constant (µmol/liter) of PLC was 28 ± 4 in patients with CSA; 49 ± 14 in patients with CAD; and 56 ± 10 in control subjects (p < 0.05, patients with CSA vs. control subjects), whereas the maximal velocity was not different between the three groups. There were significant positive correlations between PLC activity and both basal tone (p = 0.0108) and response to ACh (p = 0.0053). Western blot analysis using membrane fraction demonstrated that 89% of PLC isoenzymes detected was of the 1 isoform.

CONCLUSIONS

Because the PLC activity measured was genetically defined and was positively correlated with coronary artery vasomotility, enhanced PLC activity may be involved in the pathogenesis of coronary spasm.

Abbreviations and Acronyms   ACh = acetylcholine   CAD = coronary artery disease   CSA = coronary spastic angina   IP3 = inositol 1,4,5-trisphosphate   ISDN = isosorbide dinitrate   Km = Michaelis constant   PIP2 = phosphatidyl inositol 4,5-bisphosphate   PKC = protein kinase C   PLC = phospholipase C   Vmax = maximal velocity of reaction

This article has been cited by other articles:

				T. Nakano, T. Osanai, H. Tomita, M. Sekimata, Y. Homma, and K. Okumura Enhanced Activity of Variant Phospholipase C-{delta}1 Protein (R257H) Detected in Patients With Coronary Artery Spasm Circulation, April 30, 2002; 105(17): 2024 - 2029. [Abstract] [Full Text] [PDF]