Attenuation by propranolol of exercise training effects in spontaneously hypertensive rats.

The effects of propranolol (10 mg/kg) on systolic blood pressure (SBP), resting and exercising heart rates (HR), and body weight (BW) were examined in 11-week swim-trained spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. In both species, SBP was significantly reduced by either propranolol or training, but the reduction was greater with propranolol than with training. However, when propranolol was administered to rats during training, their independent beneficial effects on SBP were annulled. HR was modified slightly by propranolol and training, but they both decreased BW. The mechanism of propranolol action on BW is not clear. Maximum oxygen uptake (VO2 Max), relative heart weight (RHW), and absolute heart weight (AHW) were measured after 11 weeks of training. In both SHR and WKY rats, VO2 Max was elevated by exercise training; moreover, VO2 Max was greatest among those receiving propranolol while training. However, the combined effects of propranolol and training produced a significant reduction of AHW in SHR. The RHW was increased by training, but it was decreased by propranolol. SHR rats were more sensitive to the effects of training and propranolol than WKY rats. In humans, several observations have been reported on the attenuation of certain exercise-induced cardiovascular and metabolic changes by beta-adrenergic blocking agents. Our results obtained with rats confirm some of those observations. It would seem that the hypertensive strain of rats could serve as a model for the study of attenuation mechanisms by beta-adrenergic blockers.

Radioimmunoassay of arginine vasopressin, oxytocin and arginine vasotocin-like material in the human pineal gland.

Specific radioimmunoassays (RIAs) have been developed for arginine-vasopressin (AVP), oxytocin (OT), and arginine-vasotocin (AVT): they can detect 2.5 pg, 5 pg and 1 pg of hormone respectively. The three antisera employed in the RIAs in the present study all had a specificity that discriminated between the three neuropeptides and thus allowed their accurate measurement in each of 157 human pineal glands. Immunoreactive AVP was found to have a mean concentration of 306.4/+-27.6 (SE) pg/gland in the 1389 pineals where it was at level higher than the detection limit. Immunoreactive OT was determined as 386.3/+-42.1 pg/gland in the 110 pineals where it was measurable, and the mean apparent immunoreactive AVT content was 44.6/+-3.6 pg/gland in the 110 pineals where it was found at detectable levels. Cross-reactivity with AVP or OT cannot account for the immunoreactive peptide content of human adult pineal glands was demonstrated as a function of: (1) sex, (2) time of death, (3) cause of death, (4) age (18 to 85 yr old) or (5) delay between death and gland removal over the range of 4 to 48 hr. While the presence of AVP and OT is not surprising, indications of an immunoreactive AVT may in fact reflect a peptide which is closely related to AVT and cross-reacts in the AVT RIA.

[Urinary elimination of oxytocin and vasopressin measured by radioimmunoassay in different phases of the menstrual cycle in women]. / Elimination urinaire d'ocytocine et de vasopressine mesurées par radioimmunodosage au cours des différentes phases du cycle menstruel chez la femme.

Urinary arginine-vasopressin (AVP) and oxytocin (OT) excretion were measured by radioimmunoassay and studied in 3 normally cycling women. No difference for AVP and OT excretion was found between the different phases of the menstrual cycle. But in one subject with a typical pre-menstrual syndrom (weight gain of 1.5 kg), a significant statistical difference was found in AVP excretion (p less than 0.05) between the pre-ovulatory (25.3 +/- 3.08 ng/24 h) and the post-ovulatory (39.45 +/- 5.59 ng/24 h) phase. The well known stimulatory effect of estrogen as judged from plasma studies on neurohypophyseal hormones was thus difficult to demonstrate in urine. These results could be explained by the fact that the kidney destroys both AVP and OT, but OT at a higher rate than AVP.