Reduced Myocardial Sarcoplasmic Reticulum Ca ²⁺ -ATPase mRNA Expression and Biphasic Force-Frequency Relations in Patients With Hypertrophic Cardiomyopathy

Abstract

Background-The relationship between left ventricular (LV) contractile functional reserve and gene expression ofCa 2ϩ -handling proteins in patients with hypertrophic cardiomyopathy (HCM) remains to be clarified. Methods and Results-We calculated the maximum first derivative of LV pressure (LV dP/dt max ) and the LV pressure half-time (T 1/2 ) during pacing in 14 patients with nonobstructive HCM (LV ejection fraction Ͼ55%) and 7 control subjects. Endomyocardial tissue was obtained, and mRNA levels of sarcoplasmic reticulum Ca 2ϩ -ATPase (SERCA2), ryanodine receptor-2, phospholamban, calsequestrin, and Na ϩ /Ca 2ϩ exchanger were quantified by use of a real-time quantitative reverse transcription-polymerase chain reaction method. Group A consisted of 7 HCM patients who showed a progressive rise in the LV dP/dt max with increased heart rate. Group B consisted of 7 HCM patients in whom the heart rate-LV dP/dt max relation was biphasic at physiological pacing rates. Both the mean maximal wall thickness and the LV hypertrophy score in group B were greater than in group A (20Ϯ5 versus 15Ϯ3 mm and 7Ϯ1 versus 5Ϯ2 points, respectively). SERCA2 mRNA levels were significantly lower in group B (SERCA2/GAPDH ratio 0.34Ϯ0.15) compared with group A (0.72Ϯ0.27) and control subjects (0.85Ϯ0.47), whereas the mRNA expression of ryanodine receptor-2, phospholamban, calsequestrin, and Na ϩ /Ca 2ϩ exchanger were similar in all groups. Conclusions-These results suggest that downregulation of SERCA2 mRNA, resulting in altered Ca 2ϩ handling, may contribute to impaired LV contractile reserve in HCM patients with severe hypertrophy, even in the absence of detectable baseline systolic dysfunction. (Circulation. 2001;104:658-663.)

Nicorandil Promotes Myocardial Capillary and Arteriolar Growth in the Failing Heart of Dahl Salt-Sensitive Hypertensive Rats

“…cDNA was synthesized from 2 g of total RNA with the use of an oligo(dT) primer and SuperScript II reverse transcriptase (Gibco BRL). Quantitative polymerase chain reaction (PCR) analysis was performed with a Prism 7700 Sequence Detector (Perkin-Elmer) as described, 21 with primers and TaqMan probes specific for cDNAs encoding atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), ␤-myosin heavy chain (␤-MHC), VEGF, or the VEGF receptor fetal liver kinase-1 (KDR). 18,22 PCR was also performed with oligonucleotides specific for endothelial NO synthase (eNOS) cDNA (5Ј-CCGGAGAATGGAGAGAGCTTT-3Ј, 5Ј-CTGTCTGT-GTTACTGGATTCCTTCC-3Ј, and 5Ј-CCTGAGCAGCACAAGA-GTTACAAAATCCGA-3Ј as the forward primer, reverse primer, and TaqMan probe, respectively; GenBank accession No.…”

Usefulness of Serum Cardiac Troponins T and I to Predict Cardiac Molecular Changes and Cardiac Damage in Patients With Hypertrophic Cardiomyopathy

“…We previously reported that the myocardial abundance of sarcoendoplasmic reticulum Ca 2+ -ATPase 2 (SERCA2) mRNA is reduced in HCM patients with reduced contractile reserve. 6) In addition, we demonstrated that morphological and functional alterations in mitochondria were observed in HCM patients. 7) Indeed, increasing evidence suggests that mitochondria play an important role in the pathogenesis of heart disease.…”

“…We previously revealed that Ca 2+ -handling 6) and mitochondrial 7) mRNA may contribute to impaired myocardial contractile reserve in HCM patients. The results of this study are consistent with those of our previous studies, 6,7) suggesting that the changes in troponins, Ca 2+ -handling, and mitochondrial function may represent ongoing myocardial damage even in clinically and hemodynamically stable HCM patients.…”

Mechanism underlying the efficacy of combination therapy with losartan and hydrochlorothiazide in rats with salt-sensitive hypertension

“…Portions of the RNA (2 mg) were subjected to reverse transcription (RT) with the use of random primers (Invitrogen, Carlsbad, CA, USA) and MuLV Reverse Transcriptase (Applied Biosystems, Foster City, CA, USA). The resulting complementary DNA was subjected to real-time PCR analysis with the use of a Prism 7700 Sequence Detector (Perkin-Elmer, Waltham, MA, USA), as previously described, 23 and with primers and TaqMan probes specific for atrial natriuretic peptide (ANP), 22 brain natriuretic peptide (BNP), 22 collagen type I 24 or type III, 24 angiotensin-converting enzyme (ACE), 22 the AT 1A 22 or AT 2 (5¢-CTGGCTGTGGCTGACTTACTC-3¢, 5¢-TTTGC ACATCACAGGTCCAAAG-3¢, and 5¢-TTGGCAACCCTTCCTCTCTGGGCA-3¢ as the forward primer, reverse primer and TaqMan probe, respectively; GenBank accession no. NM_022456) receptor, transforming growth factorb1 (TGF-b1) 22 or connective tissue growth factor (CTGF).…”