vasoactive-intestinal-peptide and Arrhythmias--Cardiac

The suprachiasmatic nucleus (SCN) of the hypothalamus is the site of a central circadian clock that orchestrates overt rhythms of physiology and behavior. Circadian timekeeping requires intercellular communication among SCN neurons, and multiple signaling pathways contribute to SCN network coupling. Gamma-aminobutyric acid (GABA) is produced by virtually all SCN neurons, and previous work demonstrates that this transmitter regulates coupling in the adult SCN but is not essential for the nucleus to sustain overt circadian rhythms. Here, we show that the deletion of the gene that codes for the GABA vesicular transporter

Topics: Arrhythmias, Cardiac; Circadian Clocks; Circadian Rhythm; gamma-Aminobutyric Acid; Humans; Neurons; Suprachiasmatic Nucleus; Vasoactive Intestinal Peptide

To observe the effect of electroacupuncture (EA) on heart rate (HR), arrhythmia duration, and plasma vasoactive intestinal peptide (VIP) level in ventricular tachycardia (VT) rats so as to study its underlying adjustment mechanism.. A total of 70 SD rats were randomly divided into normal control, model (VT), "Daling" (PC 7, EA-PC 7) and "Taiyuan" (LU 9, EA-LU 9) groups. VT model was duplicated by injection of CsCI (2 mol/L, 1.6 mmoL/kg, femoral vein). EA (2 Hz/15 Hz, 1 mA) was applied to "Daling" (PC 7) and "Taiyuan" (LU 9) for 5 min after inserting acupuncture needles. BL-410 Biofunctional System was used to record the ECG of the standard limb lead II, and plasma VIP content assayed by using radioimmunoassay.. Following intravenous injection of CsCI, HR increased significantly in model, EA-PC 7 and EA-LU 9 groups (P < 0.05). Compared to model group, HR at 5 min, 10 min and 15 min after administration of CsCI and the duration of arrhythmia in EA-PC 7 group decreased considerably (P < 0.01). No significant differences were found between EA-LU 9 and model groups in HR and the duration of arrhythmia (P > 0.05). Compared with normal group, the content of plasma VIP in model group decreased apparently (P < 0.05), while in comparison with model group, plasma VIP level in EA-PC 7 group increased considerably (P < 0.01).. Electroacupuncture of "Daling" (PC7) can effectively suppress CsCI-induced tachycardia which may be closely associated with its effect in reducing plasma VIP level.

Topics: Acupuncture Points; Animals; Arrhythmias, Cardiac; Disease Models, Animal; Electroacupuncture; Electrocardiography; Female; Heart Rate; Humans; Male; Random Allocation; Rats; Rats, Sprague-Dawley; Tachycardia, Ventricular; Vasoactive Intestinal Peptide

The aim was to investigate whether intrinsic cardiac neurones can be involved in the genesis of ventricular arrhythmias.. Nicotinic, muscarinic, beta adrenergic, peptidergic, and amino acidergic agonists, as well as purinergic compounds, were individually administered in microliter quantities adjacent to spontaneously active in situ right atrial neurones in 57 anaesthetised dogs before and after acute decentralisation.. Ventricular arrhythmias were induced in one third of the dogs following neurochemical administration. Ventricular arrhythmias are induced much less frequently when intrathoracic extracardiac neurones are modified chemically. Salvos of ventricular premature contractions or ventricular tachycardias were elicited when intrinsic cardiac neurones were modified locally applied nicotine, bethanechol, isoprenaline, angiotensin II, bradykinin, substance P, vasoactive intestinal polypeptide, glutamate, or adenosine. In 60% of those instances in which intrinsic cardiac neuronal activity was modified by a neurochemical, ventricular arrhythmias were elicited. When arrhythmias were induced, activity generated by chemically modified intrinsic cardiac neurones increased from 0.7(SD 0.2) to 2.2(0.4) impulses.s-1 (p < 0.05). Following decentralisation of the intrinsic cardiac nervous system, repeat administration of the same neurochemicals into the same loci elicited ventricular arrhythmias in 42% of those dogs in which ventricular arrhythmias had been elicited previously. Neuronal activity increased [0.8(0.5) to 2.1(0.6) impulses.s-1; p < 0.05] in 86% of these instances.. Intrinsic cardiac neurones can be involved in the genesis of ventricular arrhythmias.

Topics: Adenosine; Adenosine Triphosphate; Angiotensin II; Animals; Arrhythmias, Cardiac; Autonomic Agents; Bethanechol; Bethanechol Compounds; Bradykinin; Dogs; Female; Glutamates; Heart; Isoproterenol; Male; Myocardial Contraction; Neurons; Nicotine; Peptides; Purines; Substance P; Vasoactive Intestinal Peptide

Suprachiasmatic nuclei (SCN) obtained from neonatal or embryonic 19 or 20 day rats, were grafted into the third ventricle of SCN-lesioned arrhythmic siberian chipmunks. Four out of 37 chipmunks showed reappearance of circadian rhythmicity in wheel running activity. In all 4 cases, at least one surviving graft was confirmed in the host brain. Also, vasopressin and vasoactive intestinal polypeptide (VIP)-like immunoreactive substances were found in the graft, suggesting the existence of live SCN neurons. Although the number of successful cases and the intensity of the restored rhythm was limited compared to the intra-species grafting in rats, a possibility that cross-species transplantation of SCN can restore circadian rhythmicity was shown.

Topics: Animals; Arrhythmias, Cardiac; Brain Tissue Transplantation; Circadian Rhythm; Fetal Tissue Transplantation; Immunohistochemistry; Male; Motor Activity; Rats; Sciuridae; Suprachiasmatic Nucleus; Transplantation, Heterologous; Vasoactive Intestinal Peptide; Vasopressins