@article{FeuersteinSiren1987, author = {Feuerstein, G. and Sir{\´e}n, Anna-Leena}, title = {Cardiovascular effects of enkephalins}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-49048}, year = {1987}, abstract = {Enkephalins and their receptors are found in neurons and nerve terminals known to be involved in central cardiovascular control as well as the peripheral sympathetic and parasympathetic systems. Enkephalins and opioid receptors were also iden tified in the heart, kidneys, and blood vessels. The enkephalins interact with several specific receptors, of which p, 0, and K have been best characterized. Enkephalins administered to humans or animals produce cardiovascular effects which depend on the spedes, route of administration, anesthesia, and the selectivity for receptor subtype. While little information exists on the role of enkephalins in normal cardiovascular control, current data suggest that enkephalins might have a role in cardiovascular stress responses such os in shock and trauma.}, subject = {Medizin}, language = {en} } @article{FeuersteinSiren1986, author = {Feuerstein, G. and Sir{\´e}n, Anna-Leena}, title = {Effect of naloxone and morphine on survival of conscious rats after hemorrhage}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48669}, year = {1986}, abstract = {The endogenous opioid system has been reported to depress the cardiovascular system during shock states, since naloxone, a potent opiate antagonist, enhances recovery of hemodynamic variables in various shock states. However, the effect of naloxone on long-term survival of experimental animals exposed to hypovolemic hypotension is not clear. The present studies tested the capacity of various doses of naloxone to protect conscious rats from mortality following various bleeding paradigms. In addition, the effect of morphine on survival of rats exposed to hemorrhage was also examined. In the six different experimental protocols tested, naloxone treatments failed to improve short- or long-term survival; in fact, naloxone treatment reduced short-term survival in two of the experimental protocols. Morphine injection, however, enhanced the mortality of rats exposed to hemorrhage in a dose-dependent manner. It is concluded that while opiates administered exogenously decrease survival after acute bleeding, naloxone has no protective action in such states and, like morphine, it may decrease survival in some situations.}, subject = {Medizin}, language = {en} } @article{FeuersteinSirenGoldsteinetal.1989, author = {Feuerstein, G. and Sir{\´e}n, Anna-Leena and Goldstein, DS and Johnson, AK and Zerbe, RL}, title = {The effect of morphine on the hemodynamic and neuroendocrine responses to hemorrhagic shock in conscious rats}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-49033}, year = {1989}, abstract = {We have previously reported that analgesic doses of morphine accelerate mortality of rats exposed to hemorrhage (Feuerstein and Siren: Circ Shock 19:293-300, 1986). To study the potential mechanisms involved in this phenomenon, rats were chronically implanted with catheters in the femoral vessels and morphine (1.5 or 5 mg/kg) was administered 30 min or 24 hr after bleeding (8.5 mll300 g over 5 min) while arterial blood pressure and heart rate were continuously monitored. Furthermore, the effect of morphine (5 mg/kg) on cardiac output (CO) response to hemorrhage was studied in rats chronically equipped with a mini thermistor for CO monitoring by a thermodilution technique. In addition, plasma catecholamines (HPLC), plasma renin activity (PRA, RIA), vasopressin (RIA), pH, and blood gases were also determined. Morphine administration 30 min after hemorrhage produced a pressor response and tachycardia which were in marked contrast to its depressor effect in intact rats. Morphine elevated PRA and epinephrine but not vasopressin, while blood pH and gases showed no consistent change as compared to salinetreated hemorrhaged rats. Morphine given after the bleeding resulted in enhanced cardiac depression in response to a second bleed of 2 m1l300 g. Our data suggest that activation of pressor mechanisms by morphine during hypovolemic hypotension might enhance vasoconstriction in essential organs, depress cardiac function, and further reduce effective tissue perfusion.}, subject = {Medizin}, language = {en} }