Detection of stress and the effects of central nervous system depressants by gastrointestinal smooth muscle electromyography in wakeful rats.

AIMS: The altered gut-brain interaction can be in the background of functional gastrointestinal (GI) disorders. In the GI tract, the slow-wave myoelectric signals can be detected by electromyography (EMG). The aims of our study were to follow up the stress induced alteration in the GI tract by smooth muscle EMG in wakeful rats. MAIN METHODS: The GI tract myoelectric activity of male rats was measured by an electrode pair under the abdominal skin, the responses were detected and analyzed by a software using fast Fourier transformation. Animals were immobilized and treated with either diazepam or haloperidol. The plasma corticosterone level was determined by ELISA kit, the levels of drugs were measured by HPLC, while the direct GI effects of the compounds were tested in an organ bath. KEY FINDINGS: Significant correlation (r2 = 0.52) was found between the immobilization induced increase in the EMG spectra of the GI tract segments and the increase in corticosterone plasma levels. The stress-reducing effects of diazepam and haloperidol were also detectable by smooth muscle EMG in the GI tract. No direct smooth muscle actions of the drugs were found in organ bath studies. SIGNIFICANCE: The smooth muscle EMG instrument can measure the level of acute stress and is applicable for the investigation of central nervous system affecting drugs through the GI tract in awake rats. This is the first tool to measure the stress response via the GI tract reactions. The technique may open a new perspective in the diagnosis and therapy of psychosomatic disorders.

The role of the myocardial water content in heart function.

In previous experiments a considerable interstitial oedema developed after myocardial infarction followed by the infusion of 6 mmol/kg/min norepinephrine lasting for 10 min in the 2nd and 48th hours as well as after a 60 min period of ventricular fibrillation during cardiopulmonary bypass. On the other hand myocardial dehydration was induced by hyperosmolality of 320-470 mOsm/l caused by mannitol or glucose after pancreatectomy. A close bilinear correlation was found between the myocardial water content and the increase of ventricular diastolic stiffness. It was further established that the increase of ventricular stiffness is followed by a decrease of the cardiac output index measured during left ventricular afterload. The cardiac output index was lower after myocardial infarction and pancreatectomy than during cardiopulmonary bypass or mannitol-treatment. Of clinical importance is the fact that ventricular performance decreases when myocardial water content exceeds or does not reach the value of 760-790 g water per 1000 g myocardium.

Compensatory hyperkinesis of the ventricular walls in acute myocardial ischaemia.

After ligation of the anterior descending coronary artery in dogs, conductance of the left circumflex branch and contractility of the ventricular muscular areas supplied by the left descending coronary artery and its circumflex branch were studied over 60 min. After ligation a considerable increase in contractility of the myocardial areas of the posterior wall with intact blood supply was found and a further increase parallel with a considerably enhanced flow in the circumflex branch. At the same time the contractile power of the anterior ventricular myocardium with a poor blood supply greatly decreased. A close correlation was found between the increase in flow in the circumflex branch and the increase in contractility of the intact areas. The tissue catecholamine level showed a marked increase in the myocardial areas with impaired blood supply.