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Derk-Jan Dijk 《Seminars in cell & developmental biology》1996,7(6):831-836
Human physiology and behavior are characterized by a daily internal temporal dimension. This so-called circadian rhythmicity is present for almost all variables studied to date, persists in the absence of external cycles, and is synchronized to the external 24-h world by an internally generated circadian rhythm of light sensitivity. The light-sensitive circadian pacemaker, presumably also in humans located in the suprachiasmatic nucleus of the hypothalamus, drives the endogenous circadian component of rhythmicity for a number of variables including plasma melatonin, alertness, sleep propensity and sleep structure. Overt rhythmicity and the consolidation of vigilance states are generated by a fine-tuned interaction of this circadian process with other regulatory processes such as sleep homeostasis. 相似文献
3.
Yang Ping He Yu-quan Zeng Hong Ni Jin-song Yun Qing-jun Huang Xiao-ping Li Shu-mei .Cadiovascular Department China-Japan Union Hospital of Jilin University Changchun P. R. China . Department of Pathdogy School of Basic Medical Sciences of Jilin University Changchun P. R. China . Cardiovascular Department Second Hospital of Jilin University Changchun P. R. China 《仿生工程学报(英文版)》2005,2(2):87-91
1Introduction Congestiveheartfailureisamultipleaetiology,high prevalence,cardiovasculardisorderwithpoorprognosis. Medicaltreatmentofdilatedcardiomyopathyisaimedat alleviatingthesymptomsofheartfailure.Diuretics,ACE inhibitorsandbeta blockershavefavourableeffectson symptoms,exercisecapacityandmortality[1-3].Growth hormone(GH)andinsulin likegrowthfactor(IGF) 1 areinvolvedinseveralphysiologicalprocessessuchas thecontrolofmusclemassandfunction,bodycomposi tionandtheregulationofnutrientmetaboli… 相似文献
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应用全细胞膜片钳技术,研究了M胆碱能对不同孕期的胚胎小鼠心肌细胞的起搏电流(If)的调节。我们发现,在胚胎发育的早期阶段,M胆碱能受体激动剂(muscarinic agonist carbachol,CCh)明显抑制If,但在胚胎发育的晚期阶段,CCh对If的抑制作用消失。腺苷酸环化酶(adeinylate cyclase,AC)激动剂毛喉素Forskolin和非选择性磷酸二酯酶(PDE)抑制剂IBMX均可增强发育早期阶段和晚期阶段的If。但有趣的是,尽管,Forskolin和IBMX可增加基础If,它们对CCh抑制的If的作用却大不相同。在胚胎发育的早期阶段,Forskolin不能拮抗CCh对If的抑制作用,但IBMX可以。在发育的中期阶段Forskolin可以拮抗CCh的抑制作用,但IBMX不可以。因此,我们推断,CCh可能是通过调控细胞内的CAMP水平来调节If的。但是在胚胎发育的早期阶段和中期阶段,CCh可能通过不同的信号转导通路来实现对胞内cAMP的水平调控。在发育的早期阶段,CCh主要是通过增强PDE的活性,加速cAMP的降解而实现对f的调控。而在发育的中期阶段,CCh则主要通过与AC耦联,抑制其活性,通过减慢cAMP的合成而实现对If的调控。 相似文献
5.
Interstitial cells of Cajal (ICCs) are the pacemakers of the gastrointestinal tract, and transient receptor potential melastatin type 7 (TRPM7) and Ca2+ activated Cl− channels (ANO1) are candidate the generators of pacemaker potentials in ICCs. The effects of D-erythro-sphingosine (SPH) and structural analogues of SPH, that is, N,N-dimethyl-Derythro-sphingosine (N,N-DMS), FTY720, and FTY720-P on the pacemaking activities of ICCs were examined using the whole cell patch clamp technique. SPH, N,N-DMS, and FTY720 decreased the amplitudes of pacemaker potentials in ICC clusters, but resting membrane potentials displayed little change. Also, perfusing SPH, N,N-DMS, or FTY720 in the bath reduced both inward and outward TRPM7-like currents in single ICCs, and inhibited ANO1 currents. The another structural analogue of SPH, FTY720-P was ineffective at the pacemaker potentials in ICC clusters and the TRPM7-like currents in single ICCs. Furthermore, FTY720- P had no effect on ANO1. These results suggest that SPH, N,N-DMS, and FTY720 modulate the pacemaker activities of ICCs, and that TRPM7 and ANO1 channels affect intestinal motility. 相似文献
6.
Partha Prateem Choudhury Vivek Chaturvedi Saibal Mukhopadhyay Jamal Yusuf 《Indian pacing and electrophysiology journal》2014,14(4):217-222
A 58 year old male, known case of type 2 diabetes and hypertension, had undergone implantation of a dual chamber pacemaker(DDDR) in 2007 for complaints of recurrent syncope and trifascicular block with a normal ejection fraction andnormal coronaries. His post implantation parameters were normal at that time.He now presented to our pacemaker clinic where his ECG done showed two types o fpaced complexes. The first few complexes were consistent with atrial sensed right ventricular apical pacing with left superior axis. Later complexes showed loss of atrial sensing with pacing from right ventricular outflow tract(inferior axis) with subtle oscillation in it''s axis. On application of magnet, two pacemaker spikes were visible withinterspike interval of 120 ms and paced complexes with inferior axis starting from the first spike suggesting that the atrial lead was responsible for RVOT depolarization. On interrogation of the pacemaker, atrial EGM showed sensed activity from atrium followed by large sensed ventricular complex. Fluoroscopy confirmed that the atrial lead was dislodged and was intermittently prolapsing into the RVOT. Since the patient was asymptomatic, he refused any intervention and subsequentlyhis atrial lead was switched off by telemetry. The above case signifies that asymptomatic lead dislodgement is no talways manifested as loss of capture and even subtle variation of the axis o fthe paced complexes can provide us with a clue that can be confirmed by telemetry of the pacemaker and fluoroscopy. 相似文献
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目的:观察在缺血条件下,溶血磷脂酰胆碱(LPC)对心肌起搏离子流(If)的影响以及能否被异丙肾上腺素(ISO)逆转.方法:采用双微电极电压钳制术,在各钳制电位测定并比较缺血心肌加入LPC和LPC加ISO的起搏离子流(If)幅值.结果:缺血降低If幅值,在模拟缺血液中加入LPC 2×10-5mol/L,If幅值在Ec -80~-120 mV水平进一步显著降低(n=5,P<0.05),加重了缺血对If离子流的抑制作用.在模拟缺血液中同时加入LPC 2×10-5mol/L和ISO 1×10-6mol/L,If幅值在Ec -90~-120 mV水平比模拟缺血时有显著增加(n=8,P<0.05),但未能达到缺血前基础水平.结论: 急性心肌缺血时,毒性代谢产物 LPC 加重起搏离子流的受抑程度,即使局部儿茶酚胺大量释放和积聚,也不能完全逆转上述抑制效应. 相似文献
9.
Kenji Tomioka Kenji Yamada Shinya Yokoyama Yoshihiko Chiba 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1991,169(3):291-298
The coupling mechanism between the bilaterally paired optic lobe circadian pacemakers in the cricket Gryllus bimaculatus was investigated by recording locomotor activity, under constant light or constant red light, after the optic nerve was unilaterally severed.
These results suggest that the 2 optic lobe pacemakers weakly couple to one another and that the cricket maintains a stable temporal structure in its behavior through the phase-dependent mututal inhibition of activity and the phase-dependent freerunning period modulation. 相似文献
1. | The majority (about 70%) of the animals showed a locomotor rhythm with 2 rhythmic components; one freerunning with a period of 25.33 ± 0.41 (SD) h and the other with 24.36 ± 0.37 (SD) h under constant light (Fig. 3A). |
2. | Removal of the intact side optic lobe abolished the longer period component (Fig. 4A), while the operation on the operated side caused a reverse effect (Fig. 4B), indicating that the longer and the shorter period components are driven by the pacemaker on the intact and the operated side, respectively. |
3. | The activity driven by a pacemaker was inhibited during the subjective day of the contralateral pacemaker (circadian time 0–10, Fig. 5). |
4. | The freerunning periods of the two components were not constant but varied as a function of the mutual phase angle relationship (Figs. 3A, 7, 8). |
10.
《Indian pacing and electrophysiology journal》2022,22(1):44-46
We present a case of 36-year-old woman with twin pregnancy, Chagas cardiomyopathy and history of multiple episodes of dizziness and syncope. The patient's Holter study revealed sinus pauses of up to 5.3 seconds, frequent premature ventricular contractions (PVC) and some episodes of non-sustained ventricular tachycardia at 110 bpm. To avoid teratogenic radiation, dual chamber pacemaker implantation was performed guided by transthoracic echocardiography. The patient was treated with metoprolol succinate 100 mg once a day to reduce PVC and nonsustained ventricular tachycardia. During follow up, the patient reported complete resolution of syncope and dizziness. She went on to have a normal delivery without complications. PCRs for Chagas in both twins were negative. 相似文献