Cardiopulmonary control in sleeping Sprague-Dawley rats treated with hydralazine

Carley, David W., Sinisa M. Trbovic, Alex Bozanich, andMiodrag Radulovacki. Cardiopulmonary control in sleepingSprague-Dawley rats treated with hydralazine. J. Appl.Physiol. 83(6): 1954-1961, 1997.To test thehypothesis that hydralazine can suppress spontaneous sleep-relatedcentral apnea, respiratory pattern, blood pressure, and heart periodwere monitored in Sprague-Dawley rats. In random order and on separatedays, rats were recorded after intraperitoneal injection of1) saline or2) 2 mg/kg hydralazine. Normalizedminute ventilation(NI)declined significantly with transitions from wake tonon-rapid-eye-movement (NREM) sleep (5.1%;P = 0.01) and rapid-eye-movement (REM)sleep (4.2%; P = 0.022).Hydralazine stimulated respiration(NIincreased by 21%; P < 0.03) andeliminated the effect of state onNI. Bloodpressure decreased by 17% after hydralazine, and the correlationbetween fluctuations in mean blood pressure andNI changedfrom strongly positive during control recordings to weakly negativeafter hydralazine (P < 0.0001 foreach). Postsigh and spontaneous apneas were reduced during NREM and REMsleep after hydralazine (P < 0.05 for each). This suppression was strongly correlated with the reductionin blood pressure and with the degree of respiratory stimulation. Weconclude that mild hydralazine-induced hypotension leads to respiratory stimulation and apnea suppression.

     

Neurobiology of sleeping sickness

The advanced stages of sleeping sickness are correlated with a spread of trypanosomes into the central nervous system (CNS), producing a disseminated encephalitis. Inflammatory reactions extend along the blood vessels causing perivascular cuffing, which consists of in filtrations and proliferations of lymphocytes and also increased numbers of astrocytes and microglia. Progress in our understanding of the functions of astrocytes suggests that they are efficient antigen-presenting cells, initiating and regulating the intracerebral inflammatory response and limiting parasite spread to the perivascular spaces.     

Sex differences in the reactions to sleeping in pairs versus sleeping alone in humans

Sleep and Biological Rhythms - Couples sleeping in pairs is a modern phenomenon with potential side-effects on sleep structure and circadian rhythms. In order to examine its effects, 10 healthy...     

Waking up to sleeping sickness

Devastating epidemics of human African trypanosomiasis are currently re-emerging in many sub-Saharan countries. In the past three decades, clinical research into this important disease has been neglected, as have urgently needed initiatives on drug development, disease surveillance and vector control. Recent impetus has aimed to provide a free supply of antitrypanosomal drugs, to develop a new orally active trypanocidal agent and to attack the tsetse vector with modern technology. In addition, pan-African initiatives to co-ordinate control efforts have begun. These all provide some hope for the future, but they might not be enough to reverse the resurgence of this deadly disease in the heart of Africa.     

Spider monkey sleeping sites: Use and availability

The behavior of spider monkeys (Ateles geoffroyi) at sleeping sites and the characteristics of these sites were studied in Santa Rosa National Park, Costa Rica. The spider monkeys tended to congregate just prior to dusk at a number of sleeping sites which were repeatedly used (81.6%), but occasionally they slept in trees which were only used once (18.4%). All of the regularly used sleeping trees were not used concurrently, but rather, there was a rotation between sites. In general, males were not encountered at regularly used sleeping sites as often as other age/sex classes, and when they were in all male subgroups, they did not sleep in repeatedly used sites. The trees used as regular sleeping sites tended to be large, but such trees were common in the group's home range. The size of the subgroups attending repeatedly used sleeping trees was large when food was abundant and small when food was scarce. It is suggested that this relationship reflects that the costs of travelling to the sleeping site would be more easily recovered when food was abundant than when food was scarce.