Influence of the central benzodiazepinergic system on peripheral cardiovascular regulation

Diazepam is known to have cardiovascular depressive effects through a combined action on benzodiazepinergic receptor and the GABA receptor-chloride ion channel complex. Moreover, it is known that barbiturates also have some cardiovascular regulatory effects mediated by the central GABAergic system. Therefore, this study was undertaken to delineate the regulatory actions and interactions of these systems by measuring the responses of the cardiovascular system and renal nerve activity to muscimol, diazepam and pentobarbital, administered intracerebroventricularly in rabbits. When muscimol (0.03~-0.3 microgram/kg), diazepam (10~100 microgram/kg) and pentobarbital (1-10 microgram/kg) were injected into the lateral ventricle of the rabbit brain, there were similar dose-dependent decreases in blood pressure (BP) and renal nerve activity (RNA). The relative potency of the three drugs in decreasing BP and RNA was muscimol > pentobarbital >diazepam. Muscimol and pentobarbital also decreased the heart rate in a dose-dependent manner; however, diazepam produced a trivial, dose-independent decrease in heart rate. Diazepam (30 microgram/kg) pentobarbital (3 microgram/kg) did not. Bicuculline (0.5 microgram/kg), a GABAergic receptor blocker, significantly augmented the effect of muscimol (0.1 microgram/kg) in decreasing blood pressure and renal nerve activity, but of pentobarbital in decreasing BP and RNA, either alone or with muscimol. We inferred that the central benzodiazepinergic and barbiturate systems help regulate peripheral cardiovascular function by modulating the GABAergic system, which adjusts the output of the vasomotor center and hence controls peripheral sympathetic tone. Benzodiazepines more readily modulate the GABAergic system than barbiturates.

Clinical Analysis of Anterior Approach with the Several Types of Cervical Plate for the Lower Cervical Lesions

The surgical approach to the lower cervical lesions, especially in traumatic injuries, has been controversial. Some authors advocated posterior fusion for such lesions, while others disagreed and reported good operative results with anterior approach using several types of cervical plates. We analysed 28 patients with lower cervical spine traumatic as well as pathological lesions who underwent 32 anterior surgical interventions with cervical plates during the period of August, 1991 and December, 1993. A successful postoperative vertebral stability was obtained in 5 patients(89.3%) and in 19 patients(87.5%) who had predominent posterior ligamentous injuries. Serious complications such as esophageal perforation and postoperative angulation were seen in 5 patients(17.3%) that were related to the process of reduction. With our clinical experiences, we support anterior fusion with cervical plates particularly for lower cervical lesions even though posterior fusion has ben preferred for traumatic posterior ligamentous complex injuries.

A Case of Lateral Ventricle Choroid Plexus Papilloma in an Infant

Choroid plexus papillomas are uncommon neoplasms of the central nervous system, accounting for 0.4% to 0.1% of all intracranial tumors. We present a choroid plexus papilloma in the trigone of the lateral ventricle in an 8 months old infant with hydrocephalus. We successfully controlled hydrocephalus and subdural fluid collection after total removal of the mass.

Pressor Effect of Intracerebroventricular Diphenhydramine and Ranitidine in Rabbits

This study was undertaken to observe the effects of centrally administred antihistamines on the blood pressure. Diphenhydramine(DPH), a H1-receptor antagonist, and ranitidine(RAN), a H2-receptor antagonist were administered intracerebroventricularly(icv) on urethane-anesthetized rabbits. 1) Both DPH and RAN administered intraccebroventricularly increased blood pressure, however the intravenous(iv) adminstration of them did not affect blood pressure. The pressor response to icv DPH was dose-dependent, but that to icv RAN was not. 2) The pressor response to icv DPH(1mg) was either markedly attenuated or reversed to depressor response by the pretreatment with icv phentolamine(250,500ug), and iv chlorisondamine(0.1, 1mg/Kg) and iv phenoxybenzamine(1mg/Kg). In cord-sectioned rabbtis, icv RAN) 1mg) did not produce pressor response. 3) The pressor responsr to icv RAN(1mg) was not affected by the pretreatment with icv phentolamine(500ug), iv chlorisondamin(1mg/Kg) and iv phenoxybenzamine(1mg/Kg), and iv phenoxybenzamine(1mg/Kg). RAN also producted pressor response in cordsectioned rabbits. These results suggest that the pressor response to icv DPH is elecited by increasing peripheral sympathetic tone via the stimulation of central alpha-adrenoreceptors and the pressor response to icv RAN is produced by releasing some humoral facotr which can increase blood pressure.