1 The perivascular nerves of isolated tail arteries from Wistar rats were stimulated with field pulses (1 Hz, 2 pulses, every 2 min). w-Conotoxin 1Onmol depressed neurogenically mediated contractions, but did not influence the contractions to noradrenaline 0.1-0.3 pmol -1.2 The inhibitory effect of cw-conotoxin was concentration-dependent (IC50 = 3.8nmollP). It did not reach a steady-state during 30min incubation and could not be reversed upon subsequent washout for another 60 min. 3 A gradual increase in the Ca2 + concentration of the medium from 1.25 mmol I -' to 10 mmol I1 enhanced vasoconstriction and attenuated the action of w-conotoxin 10nmoll-'. When a low stimulation intensity (120mA) was used at high external Ca2+ (10 mmollP1), similar contractile responses were obtained as under normal conditions (200mA current, 2.5mmoll-' Ca2 ). However, the inverse relationship between the effect of the toxin and external Ca2+ remained unchanged. 4 The time-course and degree of the inhibition by co-conotoxin 3nmollP1 was identical in tail arteries of spontaneously hypertensive rats (SHR) and their normotensive controls (WKY). 5 When tail arteries of Wistar rats were preincubated with [3H]-noradrenaline, field stimulation (0.4 Hz, 24 pulses, every 16 min) evoked tritium overflow and vasoconstriction. cw-Conotoxin 30 nmol I -1 inhibited both responses to a similar extent.6 Our results suggest that (o-conotoxin selectively blocks Ca2 + channels in the terminals of perivascular nerves and thereby reduces the release, but not the contractile effect of the sympathetic transmitter.

Patients with severe trauma or polytrauma frequently acquire alterations in immune functions which are correlated to dysbalanced cytokine synthesis. In these settings the role of polymorphonuclear neutrophil granulocytes (PMN) as cytokine-producing cells is less well characterized. The immunosuppressive role of interleukin (IL)-10 is well known, and increased systemic IL-10 levels are related to the severity of injury and to posttraumatic complications. We determined concentrations of IL-10 in culture supernatants of 30 individual PMN fractions isolated from 18 severely traumatized patients (15 polytraumata, Injury Severity Score: 18-41, 3 severely burned patients) admitted to intensive care units. IL-10 was analyzed by ELISA (R&D Systems, Wiesbaden, Germany). PMN were isolated from EDTA-anticoagulated peripheral blood employing a one-step procedure based on a discontinuous double Ficoll gradient. The cells [1 x 10(6)/ml RPMI 1640 supplemented with 10% fetal calf serum and 25 mM N-(2-hydroxyethyl)-piperazine-N'-(2-ethanesulfonic acid] were stimulated with 0.05% heat-killed Staphylococcus aureus (Pansorbin, Calbiochem-Novabiochem, Bad Soden, Germany) for 24 h using cell culture conditions. Our results show that PMN fractions of traumatized patients produce significantly (P<0.008) higher amounts of IL-10 (354+/-95 pg/ml, n = 30) than normal healthy donor cells (125+/-95 pg/ml, n = 7). IL-10 release from PMN fractions exceeded the release from isolated patients' peripheral blood mononuclear cells induced by similar stimulation or by stimulation with toxic shock syndrome toxin-1 (10 ng) and concanavalin A (2 microg). Our results provide evidence that PMN fractions play an active role in the development of posttraumatic immunosuppression by autocrine or paracrine mechanisms, for example, by suppressing one's own antimicrobial activities or determining the development of T-cell responses via their ability to release IL-10.