Chronic Disease ; Heart Failure ; metabolism ; Humans ; Phosphorylation ; Ryanodine Receptor Calcium Release Channel ; metabolism

OBJECTIVETo investigate the effects of sinusoidal magnetic field on isolated sarcoplasmic reticulum (SR) calcium release channel (RyR1) function.

METHODSWith the Ca2+ dynamic spectrum and isotope labeled methods, the Ca2+ release and [(3)H]-Ryanodine binding, the initial rates of NADH oxidation and the production of superoxide of SR exposed to 50 Hz sinusoidal magnetic field (MF) were investigated respectively.

RESULTS0.4 mT, 50 Hz sinusoidal MF exposure for 30 min increased SR Ca2+ release initial rate about 35% from (10.82 +/- 0.89) pmol.mg(-1) pro.s(-1) to (14.69 +/- 1.21) pmol.mg(-1) pro.s(-1); and the [(3)H]-Ryanodine binding by about 15% from (2.13 +/- 0.05) pmol/mg pro to (2.45 +/- 0.07) pmol/mg pro, which regulated by 1 mmol/L NADH with 1 mmol/L NAD+. Meanwhile MF upregulated the rate of NADH oxidation by about 22% from (0.88 +/- 0.11) x 10(-4) FI/s to (1.07 +/- 0.13) x 10(-4) FI/s and upregulated the production of superoxide by about 32% from (0.99 +/- 0.09) x 10(-5) FI/s to (1.31 +/- 0.06) x 10(-5) FI/s.

CONCLUSION0.4 mT sinusoidal MF increases the activity of RyR1 within the low redox potential environment, and promotes NADH oxidase activity and superoxide production.

Animals ; Calcium ; metabolism ; Magnetic Fields ; adverse effects ; Rabbits ; Ryanodine Receptor Calcium Release Channel ; metabolism ; Sarcoplasmic Reticulum ; metabolism ; radiation effects

AIMThe characteristics of ryanodine receptor in rat cardiac sarcoplasmic reticulum (SR) and nuclear envelope (NE) were studied.

METHODSVelocity and isopyknic gradient centrifugation was employed to fractionate rat SR and NE. Ryanodine receptor was assayed with [3H] ryanodine saturate binding to the preparations.

RESULTSThe maximal binding (Bmax) and dissociating constant (Kd) of ryanodine receptor in rat cardiac NE were, 1.7% and 60% of those in SR respectively. Phosphorylation in vitro by PKA and PKC increased Bmax of the receptors in SR by 372% and 121%, and augmented those in NE by 221% and 306%, without any effects on Kd.

CONCLUSIONRyanodine receptors were present in rat myocardial NE, with lower density and higher affinity than those located in SR, which can be activated by PKA and PKC.

Animals ; Calcium ; metabolism ; Kinetics ; Myocardium ; metabolism ; Nuclear Envelope ; metabolism ; physiology ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; Ryanodine ; metabolism ; Ryanodine Receptor Calcium Release Channel ; metabolism ; Sarcoplasmic Reticulum ; metabolism ; physiology

OBJECTIVETo examine the effects of procaine and lidocaine on intracellular Ca(2+) release from sarcoplasmic reticulum ryanodine-sensitive Ca(2+) stores.

METHODSThe experiment was performed on hippocampal slices from 60-80 g male Mongolian gerbils. Levels of intracellular Ca(2+) concentration in the slices were measured by microfluorometry. The slices were perfused with 50 mmol/L KCl containing medium for 30 seconds. Then, the medium was switched to physiological medium. After 5 min of incubation, the slice was perfused with 20 mmol/L caffeine containing physiology medium for 2 min. Following incubation, the slice was superfused with physiological medium until the end of the experiment. The effects of procaine and lidocanin (100 micro mol/L) on caffeine-evoked Ca(2+) release were evaluated by adding them to the medium after high K(+) medium perfusion.

RESULTSCaffeine induced a marked increase in intracellular Ca(2+) concentration which was then decreased 12% upon the addition of procaine (P < 0.05); however, lidocaine, did not induce a similar inhibitory reaction.

CONCLUSIONProcaine inhibits ryanodine-receptor mediated Ca(2+) release from intracellular Ca(2+) stores, while lidocaine may inhibit Ca(2+) release through other mechanisms.

Anesthetics, Local ; pharmacology ; Animals ; Calcium ; metabolism ; Gerbillinae ; Hippocampus ; drug effects ; metabolism ; Lidocaine ; pharmacology ; Male ; Procaine ; pharmacology ; Ryanodine ; pharmacology ; Ryanodine Receptor Calcium Release Channel ; physiology

OBJECTIVETo investigate the abnormal abundances of calcium regulatory proteins in rabbit myocytes with failing hearts.

METHODSSixteen rabbits were divided into two groups: 8 rabbits with heart failure induced by volume plus pressure overload and 8 sham-operated animals. The hemodynamic parameters and cardiac structure and function were detected via catheterization and echocardiography respectively. L-type calcium channel (LTCC), Ryanodine receptor 2 (RyR2), Sarcoplasmic reticulum Ca(2+)-ATPase (SERCA2a), and Na(+)-Ca(2+) exchanger (NCX) protein abundances were determined by Western blot analysis.

RESULTSThe ratio of left ventricular mass to body weight, heart rate and left ventricular end diastolic pressure in heart failure rabbits were significantly increased compared with sham-operated rabbits (P < 0.01), but their left ventricular shorten fraction [(21.3 +/- 4.00)% vs. (36.5 +/- 1.36)%] and ejection fraction (0.45 +/- 0.07 vs. 0.70 +/- 0.02) were decreased (P < 0.01). In heart failure rabbits, the abundances of LTCC and RyR2 were significantly decreased (R(LTCC/actin): 0.287 +/- 0.029 vs. 0.624 +/- 0.009; R(RyR2/actin): 0.106 +/- 0.001 vs. 0.203 +/- 0.011; P < 0.01), whereas the expressions of SERCA2a and NCX were markedly increased (R(NCX/actin): 0.497 +/- 0.015 vs. 0.221 +/- 0.014; R(SERCA2a/actin): 0.611 +/- 0.036 vs. 0.433 +/- 0.008; P < 0.01).

CONCLUSIONSReductions of LTCC and RyR2 might contribute to risk factors of systolic dysfunction in failing hearts. In early stage of heart failure, upregulated SERCA2a and NCX protein levels may be helpful for maintaining cardiac performance.

Animals ; Calcium ; metabolism ; Calcium-Binding Proteins ; biosynthesis ; Female ; Heart Failure ; metabolism ; Male ; Rabbits ; Ryanodine Receptor Calcium Release Channel ; metabolism ; Sarcoplasmic Reticulum ; chemistry ; Sarcoplasmic Reticulum Calcium-Transporting ATPases ; metabolism

Receptor proteins in both eukaryotic and prokaryotic cells often form regular lattice or array in the membrane. Recent theoretical analyses indicate that such arrays may provide a novel mechanism for receptor signaling regulation in cells. The functional coupling between neighboring receptors could improve the signaling performance. The ryanodine receptors (RyR)/calcium release channels usually form 2-D regular lattice in the endoplasmic/sarcoplasmic reticulum membranes. Thus, RyR is a potentially good model to study the function of receptor 2-D array. In this article, we briefly review recent progresses in this research field, including RyR-RyR interaction, RyR array's function and working mechanisms. The investigations performed by new methods in our laboratory are summarized. We demonstrate that the RyR-RyR interaction is modulated by the functional states of RyRs. Accordingly, the mechanism of "dynamic coupling" of RyR array is proposed. Its possible role in RyR-mediated Ca(2+) release is discussed.
Animals ; Calcium ; metabolism ; Cations ; Humans ; Muscle, Skeletal ; drug effects ; metabolism ; Receptor Cross-Talk ; physiology ; Ryanodine Receptor Calcium Release Channel ; physiology ; Sarcoplasmic Reticulum ; metabolism

OBJECTIVETo study the expressions of ryanodine receptor 1 (RyR1) and voltage-gated calcium channel 1.3 (CaV1.3) in the corpus cavernosum smooth muscle of castrated rats and to investigate their role in androgen deficiency-related erectile dysfunction.

METHODSForty 8-week-old SD rats were equally randomized into Groups A (2-week sham-operation), B (4-week sham-operation), C (2-week castration), and D (4-week castration). After surgery, the levels of serum testosterone in different groups of rats were determined, and the expressions of RyR1 and CaV1.3 in the corpus cavernosum were detected by immunohistochemical staining and RT-PCR.

RESULTSThe levels of serum testosterone were significantly decreased in Groups C ([15.97 +/- 5.67] nmol/L) and D ([2.03 +/- 1.57] nmol/L) as compared with A ([90.54 +/- 20.13] nmol/L) and B ([120.35 +/- 30.32] nmol/L) (P < 0.05). RyR1 and CaV1.3 expressed in all the groups. RyR1 mRNA, CaV1.3 mRNA and their proteins were remarkably reduced in Groups C (0.51 +/- 0.24, 0.50 +/- 0.12, 120.36 +/- 25.78, 103.37 +/- 39.52, respectively) and D (0.33 +/- 0.15, 0.32 +/- 0.07, 67.39 +/- 30.54, 67.56 +/- 20.12, respectively) in comparison with A (1.53 +/- 0.25, 1.33 +/- 0.05, 300.96 +/- 135.12, 298.68 +/- 126.35, respectively) and B (1.37 +/- 0.23, 1.25 +/- 0.03, 330.38 +/- 128.59, 327.35 +/- 117.37, respectively) (P < 0.05). The androgen level was positively correlated with the expressions of RyR1 and CaV1.3.

CONCLUSIONAndrogen can regulate erectile function via RyR1 and CaV1.3.

Androgens ; pharmacology ; Animals ; Calcium Channels ; metabolism ; Male ; Muscle, Smooth ; drug effects ; metabolism ; Penis ; drug effects ; metabolism ; Rats ; Rats, Sprague-Dawley ; Ryanodine Receptor Calcium Release Channel ; metabolism

OBJECTIVETo study the expression of the L-type calcium channel (Cav1.3) and its receptor Ryrs1 in the corpus cavernosum of the penis in aged rats, and to explore the mechanism of age-related erectile dysfunction (ED).

METHODSWe included 10 two month-old male SD rats (Group A) and another ten 18-month-old ones (Group B) in this study, measured their serum testosterone levels and analyzed the expressions of Cav1.3 and RyR1 in the corpus cavernosum of the penis by RT-PCR and immunohistochemistry.

RESULTSThe level of serum testosterone was significantly lower in Group B than in A ([1 356 +/- 424] ng/L vs [2 744 +/- 964] ng/L, P < 0.05). Compared with the young rats, the aged ones showed significant decreases in the expressions of Cav1.3 (IA = 18.65 +/- 8.47 vs 75.48 +/- 14.28, P < 0.05), RyR1 (IA = 21.37 +/- 9.64 vs 78.23 +/- 13.57, P < 0.05), Cav1.3 mRNA (mean gray value = 0.382 +/- 0.046 vs 1.137 +/- 0.415, P < 0.05), and RyR1 mRNA (mean gray value = 0.146 +/- 0.053 vs 1.215 +/- 0.261, P < 0.05).

CONCLUSIONReduced expressions of Cav1.3 and RyR1 in the corpus cavernosum of the penis may be one of the mechanisms underlying age-related ED in aged rats.

Aging ; Animals ; Calcium Channels, L-Type ; metabolism ; Erectile Dysfunction ; metabolism ; Male ; Penis ; metabolism ; Rats ; Rats, Sprague-Dawley ; Ryanodine Receptor Calcium Release Channel ; metabolism

OBJECTIVETo determine the expressions of ryanodine receptor type 1 (RyR1) and Cav1.3 L-type calcium channel (Cav1.3) in the vaginal smooth muscle cells of castrated rats and investigate the correlation of RyR1 and Cav1.3 with estrogen in female sexual dysfunction.

METHODSForty female SD rats of 8 weeks were randomly divided into Groups A (2-week sham operation), B (4-week sham operation), C (2-week castration) and D (4-week castration). Two and 4 weeks after surgery, the serum estradiol level was determined with the automated immunochemiluminescence system and the expressions of RyR1 and Cav1.3 in the vaginal smooth muscle were detected by immunohistochemistry and RT-PCR. Gray scale ratio was used to represent the mRNA expression levels of RyR1 and Car1.3, and the optical density value to denote their protein expression levels.

RESULTSSerum estradiol was significantly decreased in Group C ([0.210 +/- 0.026] nmol/L) as compared with A ([0.505 +/- 0.053] nmol/L) (P < 0.01), and so was it in Group D ([0.130 +/- 0.031] nmol/L) in comparison with B ([0.476 +/- 0.058] nmol/L) (P < 0.01). RyR1 and Cav1.3 were expressed in all groups. The mRNA expressions of RyR1 and Cav1.3 were significantly reduced in Group C (0. 680 +/- 0.073 and 0.580 +/- 0.043) as compared with A (0.950 +/- 0.064 and 0.870 +/- 0.019) (P < 0.01), as well as in Group D (0.220 +/- 0.032 and 0.190 +/- 0.020) in comparison with B (0.890 +/- 0.072 and 0.820 +/- 0.021) (P < 0.01). The protein expressions of RyR1 and Cav1.3 were significantly down-regulated in Group C (96.67 +/- 7.75 and 87.97 +/- 6.96) as compared with A (123.69 +/- 10.66 and 106.46 +/- 8.04) (P < 0.01), and so were they in D (86.45 +/- 8.16 and 69.43 +/- 8.30) in comparison with B (109.31 +/- 9.87 and 97.38 +/- 7.56) (P < 0.01).

CONCLUSIONBoth RyR1 and Cav1.3 were expressed in the vaginal smooth muscle cells of the rats, and estrogen might be involved in the regulation of female sexual reaction by acting on the expressions of RyR1 and Cav1.3.

Animals ; Calcium Channels ; metabolism ; Estrogens ; blood ; Female ; Myocytes, Smooth Muscle ; metabolism ; Ovariectomy ; Rats ; Rats, Sprague-Dawley ; Ryanodine Receptor Calcium Release Channel ; metabolism ; Vagina ; cytology

This study aimed to explore the positive inotropic effect of phosphodiesterase type 9 (PDE9) inhibitor PF-04449613 in ratsand its cellular and molecular mechanisms. The heart pressure-volume loop (P-V loop) analysis was used to detect the effects of PF-04449613 on rat left ventricular pressure-volume relationship, aortic pressures and peripheral vessel resistance in healthy rats. The Langendorff perfusion of isolated rat heart was used to explore the effects of PF-04449613 on heart contractility. The cardiomyocyte sarcoplasmic reticulum (SR) Ca
Animals ; Calcium/metabolism* ; Myocardial Contraction ; Myocytes, Cardiac/metabolism* ; Phosphodiesterase Inhibitors ; Phosphoric Diester Hydrolases ; Rats ; Ryanodine Receptor Calcium Release Channel ; Sarcoplasmic Reticulum