Effects and mechanisms of L-glutamate microinjected into nucleus ambiguus on gastric motility in rats / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>L-glutamate (L-GLU) is a major neurotransmitter in the nucleus ambiguus (NA), which can modulate respiration, arterial pressure, heart rate, etc. This study investigated the effects and mechanisms of L-GLU microinjected into NA on gastric motility in rats.</p><p><b>METHODS</b>A latex balloon connected with a pressure transducer was inserted into the pylorus through the forestomach for continuous recording of the gastric motility. The total amplitude, total duration, and motility index of gastric contraction waves within 5 minutes before microinjection and after microinjection were measured.</p><p><b>RESULTS</b>L-GLU (5 nmol, 10 nmol and 20 nmol in 50 nl normal saline (PS) respectively) microinjected into the right NA significantly inhibited gastric motility, while microinjection of physiological saline at the same position and the same volume did not change the gastric motility. The inhibitory effect was blocked by D-2-amino-5-phophonovalerate (D-AP5, 5 nmol, in 50 nl PS), the specific N-methyl-D-aspartic acid (NMDA) receptor antagonist, but was not influenced by 6-cyaon-7-nitroquinoxaline-2,3-(1H,4H)-dione (CNQX) (5 nmol, in 50 nl PS), the non-NMDA ionotropic receptor antagonist. Bilateral subdiaphragmatic vagotomy abolished the inhibitory effect by microinjection of L-GLU into NA.</p><p><b>CONCLUSIONS</b>Microinjection of L-GLU into NA inhibits the gastric motility through specific NMDA receptor activity, not non-NMDA receptor activity, and the efferent pathway is the vagal nerves.</p>

Studies on effects and mechanism of water immersion restraint stress on bile secretion in rats / 中国应用生理学杂志

<p><b>AIM</b>To probe into the operation mechanism of stress, through the studies on the effects of bile secretion in rats at the condition of water immersion restraint.</p><p><b>METHODS</b>The animals were divided into six groups (n=8): Group A: restraint alone under room temperature + saline; Group B: water immersion restraint + saline; Group C: restraint alone under room temperature + Atropine; Group D: water immersion restraint + Atropine; Group E: restraint alone under room temperature + Phentolamine; F group: water immersion restraint + Phentolamine.</p><p><b>RESULTS</b>Compared with group A, the capacity of bile secretion in group B decreased significantly (P < 0.05), changes of bile increased remarkably (P < 0.01), but there were no significant decreases on the capacity of bile secretion in group C (P > 0.05) compared with A, Group C only decreased appreciably. Compared with group A, the capacity of bile secretion in group E decreased appreciably (P < 0.05). Compared with group B, the capacity of bile secretion in group D decreased significantly (P < 0.05), pH of bile had no significant changes in group D. Compared with group B, the capacity of bile secretion in group F decreased significantly (P < 0.05), pH of bile had no significant changes in group F. Compared with group D, the capacity of bile secretion and pH of bile in group F had no significant changes.</p><p><b>CONCLUSION</b>Water immersion restraint stress inhibited evidently on the capacity of bile secretion, and the capacity of bile secretion in water immersion groups decreased significantly, moreover pH of bile increased greatly. At the condition of restraint alone under room temperature, vagus and sympathetic nerve had no significant effects on the bile secretion, but they played important roles in decreases of bile secretion evidently induced by water immersion restraint stress in rats (P < 0.05).</p>

Time domain and power spectrum of wide frequency band electrocardiogram in pigeons / 生理学报

The wide frequency band ECG (WFB-ECG) was recorded in 33 (anesthetized) normal pigeons by the microprocessor ECG system (made in Nanjing University) with a wide-frequency response (0-1000 Hz), a high-speed sweep (up to 1401 mm/s) and a high sensitivity (up to 28 mm/mV). The recording methods for limb leads in the pigeon were the same as those in man, except that the needle electrodes (made by No.5 needles) were subcutaneously inserted in the bases of the wings and in the legs. We studied the features of time domain and power spectrum of pigeons WFB-ECG. It presents P, R, S and T waves, but no Q wave, basically similar to the results from Aves described by Sturkie. But there are still many characters that were not be recorded on the conventional ECG: (1) the main QRS complex is inverted and forms the type of rS or rSr , no Q wave in leads II, III, aVF, and the S-T segment is absent, which is different from that of humans. The T wave is upright in leads II, III, and aVF (except one), in agreement with that of man. But in lead aVR, the main QRS complex is upright and forms the type of Rs, and the T wave is inverted without any exception. There is a large notch on the upstroke of S wave without any exception. The amplitude of the notch is 0.413+/-0.133 mV and the duration is 9.733+/-1.291 ms in lead II. (2) The ratio of duration of P wave to P-R segment is about 0.8, lower than that of humans (1.0-1.6), but higher than that of mice (0.4). (3) The low frequency signals (0-80 Hz) are prominent. The relative power content of high frequency range of QRS in lead II is: 100-1000 Hz: (10.181+/-7.443)%; 80-300 Hz: (15.418+/-10.579)%. (4)The QRS vector loop in the frontal plane lies between -90 degrees and -180 degrees. The electrical axis of QRS complex averages -118 +/-10 (ranges from -96 degrees to -136 degrees). The reason that position of vector loop and the direction of main wave of QRS in the pigeon are different from human s and rodent s is probably that the Purkinje fibers cross the whole ventricular wall and terminate in the subepicardium in Aves including pigeons . After the impulses coming from the sinoatrial node reach the ventricular muscles, the subepicardium is depolarized before the endocardium. However in human s and rodent s, the Purkinje fibres only reach one-forth to one-second of the whole thickness from the endocardium to the epicardium, the subendocardium is depolarized before the subepicardium.