Effect of head-up tilt on cardiovascular responses in normal young volunteers.

Since the cardiovascular effects of tilting are influenced by degree as well as duration of the tilt, we planned to study the time course of blood pressure and heart rate (HR) responses during 30 degrees, 60 degrees, 80 degrees head up tilt (HUT). The study was conducted on 20 volunteers aged 18-20 y who were tilted on a tilting table. Blood pressure was determined by sphygmomanometer and HR was calculated from R-R interval of ECG. 30 degrees HUT produced an insignificant decrease in systolic pressure (SP) and pulse pressure (PP) while diastolic pressure (DP), mean pressure (MP) and rate-pressure-product (RPP) registered an insignificant rise. The changes produced by 60 degrees and 80 degrees HUT were more marked than those produced by 30 degrees HUT. While SP and PP decreased significantly, HR and RPP increased significantly. In conclusion, 30 degrees HUT produces insignificant changes while 60 degrees and 80 degrees HUT produce significant changes in SP, PP and RPP.

The effect of bilateral gastric vagotomy and histamine stimulation on parietal cell activity in streptozotocin induced diabetic rat model.

Disturbances in gastric secretions are commonly associated with diabetes mellitus and are usually attributed to autonomic neuropathy. Systematic documentation of the effects of experimental diabetes on parietal cell functions are not available. This study has been designed to evaluate the acid secretory status of the parietal cells in streptozotocin (STZ) induced rat model of diabetes mellitus by assessing the effect of bilateral gastric vagotomy and histamine administration on them. Results show that bilateral gastric vagotomy in the control rats as well as in experimental diabetes lowers the acid secreting capacity of the parietal cells. In the diabetic rats, however, vagotomy does not further decrease the gastric acid secretion. Histamine stimulation augments the acid secretory response in the controls but this rise is substantially prevented in the diabetic state. Histamine challenge following vagotomy in normal controls elicits a sharp rise in gastric acid secretion though not to the same extent as seen in rats with intact vagi. In the diabetic rats however, histamine fails to augment acid secretion after vagotomy. Diabetes is thus seen to severely impair the acid secretory response of the parietal cells and their responsiveness to histamine.

The standardized distal motor latencies and the peak to peak amplitudes of evoked muscle action potentials in the extremities of humans.

The values of Standardized Distal Motor Latency (SDML) of Median, Ulnar and Common Peroneal nerves and the peak to peak amplitude of Evoked Muscle Action Potentials (EMAP) of the small muscles of the limbs were studied in 50 normal subjects. The SDML values showed significant sex difference, whereas no sex difference was observed in the amplitude of the EMAPs.