Effect of microinjections of 5-hydroxytryptamine and adrenaline in central grey on pain responsiveness during acute food deprivation in conscious rats.

To study the effects of microinjections of 5 hydroxytryptamine and adrenaline in central grey on pain responsiveness during acute food deprivation, experiments were conducted in nine male rats. Microinjections of 5 HT (10 micrograms/microliter) and adrenaline (10 micrograms/microliter) were given in central grey before and at the end of 6, 12, 18 and 24 hr food deprivation and the effects on pain threshold, cardiorespiratory parameters and body temperature were noted. Observations showed that 5 HT increased the pain threshold (antinociception) significantly (P < 0.05) with no change in cardiorespiratory response and body temperature, adrenaline did not alter pain threshold with no change in cardiorespiratory response and body temperature. The observations suggest the possible existence of two types of monoaminergic receptors or pathways in the central grey.

Assessment of sperm count in rural population of central India.

Semen samples from 1425 males who visited the Reproductive Biology Unit, M. G. I. M. S., Sewagram during the period from 1984 to 1996 were analysed. The data for sperm count was analysed over the length of period and no change in sperm count was found with passage of time.

Effect of acute haemodilution on right atrial type-B receptor activity in anaesthetized cats.

In order to investigate whether the sensitivity of atrial type-B receptors to its natural stimulus is altered during acute haemodilution, experiments were conducted in nine anaesthetized, artificially ventilated and thoracotomized cats. Haemodilution was achieved by replacement of blood by the same volume of dextran (MW 150000). Atrial receptor activity, arterial blood pressure, right atrial pressure and ECG were recorded. Heart rate was calculated from ECG records. Arterial blood hematocrit was measured. Mean arterial blood pressure and heart rate were not altered by haemodilution even at a hematocrit level of 12.17 +/- 0.93 percent. Average activity of type-B atrial receptors, mean right atrial pressure, right atrial peak 'v' pressure, right atrial initial 'v' pressure and right atrial 'v' wave amplitude were changed significantly (r < 0.05) during acute haemodilution when the hematocrit was 12.17 +/- 0.93 percent but the atrial type-B receptor activity per cycle did not show any significant change. Average activity of type-B receptors increased from 8.56 +/- 1.02 spikes/sec to 9.56 +/- 1.11 spikes/sec. Mean right atrial pressure, right atrial 'v' wave amplitude, right atrial peak 'v' pressure increased significantly (P < 0.05) from respective control values. Right atrial initial 'v' wave pressure decreased significantly. Heart rate changed from 168.11 +/- 5.42 beats/min to 170.89 +/- 5.65 beats/min. Mean arterial pressure changed from 134.33 +/- 0.89 mmHg to 135.67 +/- 1.46 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of acute haemodilution on right atrial type-A receptor activity and right atrial pressure in anaesthetized cats.

To determine the effects of acute haemodilution on right atrial pressure and right atrial type-A receptor activity, experiments were conducted in nine anaesthetized cats. Haemodilution was induced by replacement of blood by same volume of dextran (molecular weight-150000). Arterial blood pressure, right atrial pressure and right atrial type-A receptor activity were recorded. Hematocrit, arterial blood pO2, pCO2, and pH were measured. Mean arterial blood pressure, pO2, pCO2, and pH were not altered by haemodilution which extended to a hematocrit level of about 13%. Mean right atrial pressure, 'a' wave pressure showed significant changes after 2nd and 3rd exchange. Heart rate and 'a' wave amplitude changed significantly (P < 0.05) after 3rd exchange. The amplitude of the 'a' wave was increased from 3.57 +/- 0.93 to 5.79 +/- 1.46 cm H2O, heart rate was increased from 163.89 +/- 5.36 to 169.22 +/- 4.84 beats/min, mean right atrial pressure was increased from 2.85 +/- 0.31 to 4.61 +/- 0.27 cm H2O, initial 'a' wave pressure was increased from 1.78 +/- 0.09 to 5.06 +/- 0.44 cm H2O. The data indicate that under present experimental conditions, the activity of the type-A receptor did not show any significant change (P > 0.05) on acute haemodilution. Significant increase (P < 0.05) in the amplitude of 'a' wave, mean right atrial pressure and initial 'a' wave pressure could be attributed to increased myocardial contractility.