Antidepressants are often used for the treatment of neuropathic pain. Clinical studies suggest that the efficacy of serotonin (5-HT) and noradrenaline (NA) reuptake inhibitors (SNRIs) for neuropathic pain is greater than that of selective 5-HT reuptake inhibitors (SSRIs). In the present study, we determined the efficacy and mechanisms involved in the antihyperalgesic effects of milnacipran, an SNRI, compared with paroxetine, an SSRI, and maprotiline, a selective NA reuptake inhibitor, using a rat model of neuropathic pain. Male Sprague-Dawley rats underwent spinal nerve ligation (SNL), and the withdrawal threshold to paw pressure was measured. Intraperitoneal injection of milnacipran (3-30mg/kg) produced a dose-dependent antihyperalgesic effect. The effect was reversed by intrathecal injection of the α(2)-adrenoceptor antagonist idazoxan (30μg), but not by various 5-HT receptor antagonists. Paroxetine produced an antihyperalgesic effect only at the highest dose tested (10mg/kg). This effect was reversed by intrathecal injection of both idazoxan and ondansetron (30μg), a 5-HT3 receptor antagonist. Maprotiline produced an antihyperalgesic effect (10 and 30mg/kg), and the effect was reversed by intrathecal idazoxan. In microdialysis studies, NA and 5-HT concentrations in the spinal dorsal horn were increased after injection of either milnacipran or paroxetine, and only NA was increased after maprotiline. Furthermore, the NA content in the spinal cord of SNL rats was greater than that in normal animals. These findings suggest that an increase in NA in the spinal cord plays an important role in the antihyperalgesic effects of not only NA reuptake inhibitors but also SSRIs.

Intraocular pressure (IOP) has been shown to change with body position. Several studies have shown that the lateral decubitus position (LDP) is associated with a significant increase in IOP in the dependent eye. However, whether anesthetic agents alter IOP in the LDP remains unclear. This study investigated the effect of sevoflurane and propofol anesthesia on IOP in the LDP. A total of 28 patients undergoing surgery in the LDP were included. Patients were randomly allocated to sevoflurane or propofol groups. IOP in both eyes was recorded and compared between groups at five time points: after anesthesia induction, after endotracheal intubation, at 5 min and 1 h after a positional change to the LDP, and 5 min after returning to the supine position. In the sevoflurane group, IOP was significantly increased in both dependent and non-dependent eyes 1 h after changing to the LDP. In the propofol group, IOP decreased in both dependent and non-dependent eyes after tracheal intubation, but did not increase after changing to the LDP. The number of patients in whom IOP increased to ≥28 mmHg was greater in the sevoflurane group than in the propofol group. Propofol may be better than sevoflurane for the maintenance of anesthesia in the LDP. Monitoring of IOP in the LDP might help avoid ophthalmic complications.

REPORTS OF INVESTIGATION 767CAN J ANESTH 2000 / 47: 8 / pp [767][768][769][770][771][772][773][774] Purpose: Several different anti-hypertensive regimens have been introduced for the prevention of systemic hyperdynamic responses after electrically induced seizures. In the present study, the effects of anti-hypertensive medications on cerebral circulation were studied.Methods: Systemic blood pressure was controlled by several anti-hypertensive medications, nicardipine, prostaglandin E1, alprenolol and nitroglycerin, in 30 patients (150 electroconvulsive therapy trials). Changes in cerebral blood flow velocity were measured by transcranial Doppler sonography of the right middle cerebral artery from the start of anesthesia to 10 min after the electrical shock.Results: Administration of a Ca 2+ antagonist, nicardipine, or prostaglandin E1 did not alter the augmented cerebral blood flow velocity after the seizure. However, a ß-adrenergic blocking agent, alprenolol (P < 0.05) or nitroglycerin (P < 0.01) partially inhibited the increase in cerebral blood flow velocity. Maximal blood flow velocity was 133% larger than the pre-anesthesia value in the control group, 109% in the nicardipine group, 113% in the prostaglandin E1 group, 72% in the alprenolol group, and 45% in the nitroglycerin group, respectively. The increase in cerebral blood flow velocity after electrically induced seizure was independent of systemic blood pressure. Internal jugular venous saturation (SjO 2 ) was increased, and difference in arterial and venous concentrations of lactate was not altered in all groups.Conclusions: Cerebral hemodynamics is altered by ECT, even when systemic hemodynamics are stabilized by antihypertensive medication. Although the effects of antihypertensive medicine on cerebral hemodynamics are variable, systemic blood pressure control by these agents does not induce cerebral ischemia after ECT.Objectif : Différentes thérapies antihypertensives ont été proposées comme moyen de prévention des répon-ses hyperdynamiques généralisées à la suite d'électrochocs. Dans la présente étude, on a analysé les effets de médicaments antihypertenseurs sur la circulation cérébrale.Méthode : La pression sanguine générale a été contrôlée par différents médicaments antihypertenseurs, la nicardipine, la prostaglandine E 1 , l'alprénolol et la nitroglycérine, chez 30 patients lors de 150 essais d'électro-chocs. Les changements de vitesse circulatoire cérébrale ont été mesurés par échographie Doppler transcrâni-enne de l'artère cérébrale moyenne droite, du début de l'anesthésie jusqu'à 10 min après l'électrochoc.Résultats : L'administration d'un antagoniste de Ca 2 +, la nicardipine, ou la prostaglandine E 1 n'ont pas modifié la vitesse circulatoire cérébrale augmentée après les convulsions. Toutefois, un agent ß-bloquant, l'alprénolol (P < 0,05) ou la nitroglycérine (P < 0,01) ont partiellement inhibé l'augmentation de vitesse circulatoire cérébrale. La vitesse circulatoire maximale a été 133 % de la valeur préanesthésique mesurée dans le groupe tém...