effects of atropine and methylatropine on erythropoietin production and hypothalamic stimulation in rabbits

A atropina bloqeia parcialmente o aumento na produção de EPO em coelhos submetidos a hipóxia. Na tentativa de estudar a possibilidade do envolvimento de mecanismos colinérgicos no controle da eritropoiese, a metilatropina foi administrada a coelhos, que, em seguida, foram submetidos a hipóxia hipobárica ou a estimulação do hipotálamo posterior. A metilatropina não bloqueou o aumento na produção de EPO em resposta à hipóxia, nem o aumento na taxa de reticulócitos na circulação periférica. A antropina, que atravessa a barreira hematoencefálica, bloqueia tanto o aumento na produção de EPO, quanto o aumento no número de reticulócitos na circulação periférica

Schistosoma mansoni: effects of bromolysergic acid diethylamide, verapamil, and Ca2+-free solution on the motor activity of the isolated male worm induced by electrical stimulation and oxamniquine.

Electrical stimulation and oxamniquine effect the motor activity of isolated Schistosoma mansoni. Electrical stimulation produced contractions that increased with stimulus intensity. Oxamniquine (10(-4) M) produced an increase in basal tonus and in the frequency and amplitude of the worm's spontaneous contractions. Incubation in the absence of calcium produced a decrease in the basal tonus, abolished the spontaneous contractions of S. mansoni, and abolished the mechanical response induced by electrical stimulation and oxamniquine. The effects of electrical stimulation and oxamniquine were, respectively, significantly reduced and abolished by 10(-6) M verapamil (a calcium channel blocking agent). Bromolysergic acid diethylamide (3 X 10(-5) M), a serotonin blocking agent, reduced the motor response induced by high intensity electrical stimulation and blocked the response induced by oxamniquine. The effects of low intensity electrical stimulation were not modified in the presence of bromolysergic acid. We think that external Ca2+ is important for basal tonus, for spontaneous motor activity, and for motor responses of S. mansoni induced by electrical stimulation and oxamniquine. Serotonin may be important for mechanical responses induced by high intensity electrical stimulation and for responses induced by oxamniquine.