Toxicological and Pharmacological Activities of Leptohyptis macrostachys (Benth.) Harley and J.F.B.Pastore (Lamiaceae) on Intestinal Smooth Muscle.

Leptohyptis macrostachys, previously known as Hyptis macrostachys Benth., is used in folk medicine to relieve the symptoms of asthma, cough, and bronchitis. Recently, we showed that the ethanol extract obtained from Leptohyptis macrostachys has selective spasmolytic activity on guinea pig ileum. Therefore, the aim of this study was to characterize the spasmolytic mechanism of this extract, investigated whether it presents toxicological and antidiarrheal activities. Therefore, the crude ethanolic extract of Leptohyptis macrostachys was analyzed by high-performance liquid chromatographic-diode array detection (HPLC-DAD). The spasmolytic effect was evaluated on guinea pig ileum, toxicological activity using rats and antidiarrheal activity using male and female mice. In HPLC-DAD analysis, Rosmarinic acid (5.44%) was the most abundant phenolic compound, being considered as a chemical marker. The spasmolytic potency of the extract on histamine-induced contraction was reduced in the presence of 1 mM TEA+, a selective big-conductance K+ channels blocker (BKCa). The extract produces a dose-dependent antidiarrheal activity, inhibiting equipotently defecation frequency and liquid stool formation. In addition, the extract has inhibited in a dose-dependent manner both castor oil-induced intestinal transit and intestinal fluid content. Thus, the spasmolytic activity of the extract involves positive modulation of BKCa and its antidiarrheal activity is related to inhibition of intestinal motility and secretion.

Hipertermia maligna: aspectos moleculares e clínicos / Malignant hyperthermia: clinical and molecular aspects / Hipertermia maligna: aspectos moleculares y clínicos

CONTEÚDO: A hipertermia maligna (HM) é uma doença farmacogenética potencialmente letal que acomete indivíduos geneticamente predispostos. Manifesta-se em indivíduos susceptíveis em resposta à exposição a anestésicos inalatórios, relaxantes musculares despolarizantes ou atividade física extrema em ambientes quentes. Durante a exposição a esses agentes desencadeadores, há um aumento rápido e sustentado da concentração de cálcio mioplasmático (Ca2+) induzido pela hiperativação dos receptores de rianodina (RYR1) do músculo esquelético, causando uma alteração profunda na homeostase de Ca2+, caracterizando um estado hipermetabólico. RYR1, canais de libertação de Ca2+ do retículo sarcoplasmático, é o principal local de susceptibilidade à HM. Várias mutações no gene que codifica a proteína RYR1 foram identificadas, mas outros genes podem estar envolvidos. Atualmente, o método padrão para o diagnóstico de sensibilidade à HM é o teste de contratura muscular para exposição ao halotano-cafeína (CHCT) e o único tratamento é o uso de dantroleno. No entanto, com os avanços no campo da genética molecular, um pleno entendimento da etiologia da doença pode ser fornecido, favorecendo o desenvolvimento de um diagnóstico preciso, menos invasivo, com o teste de ADN, e também proporcionar o desenvolvimento de novas estratégias terapêuticas para o tratamento da HM. Logo, esta breve revisão tem como objetivo integrar os aspectos clínicos e moleculares da HM, reunindo informações para uma melhor compreensão desta canalopatia.

CONTENT: Malignant hyperthermia (MH) is a potentially lethal pharmacogenetic disorder that affects genetically predisposed individuals. It manifests in susceptible individuals in response to exposure to Inhalant anesthetics, depolarizing muscle relaxants or extreme physical activity in hot environments. During exposure to these triggering agents, there is a rapid and sustained increase of myoplasmic calcium (Ca2+) concentration induced by hyperactivation of ryanodine receptor of skeletal muscle (RyR1), causing a profound change in Ca2+ homeostasis, featuring a hypermetabolic state. RyR1, Ca2+ release channels of sarcoplasmic reticulum, is the primary locus for MH susceptibility. Several mutations in the gene encoding the protein RyR1 have been identified; however, other genes may be involved. Actually, the standard method for diagnosing MH susceptibility is the muscle contracture test for exposure to halothane-caffeine (CHCT) and the only treatment is the use of dantrolene. However, with advances in molecular genetics, a full understanding of the disease etiology may be provided, favoring the development of an accurate diagnosis, less invasive, with DNA test, and also will provide the development of new therapeutic strategies for treatment of MH. Thus, this brief review aims to integrate molecular and clinical aspects of MH, gathering input for a better understanding of this channelopathy.

CONTENIDO: La hipertermia maligna (HM) es una enfermedad farmacogenética potencialmente letal que afecta a individuos genéticamente predispuestos. Se manifiesta en los individuos susceptibles en respuesta a la exposición a los anestésicos inhalatorios, relajantes musculares despolarizantes o actividad física extrema en ambientes calientes. Durante la exposición a esos agentes desencadenantes, existe un aumento rápido y constante de la concentración de calcio mioplasmático (Ca2+) inducido por la hiperactivación de los receptores de rianodina (RYR1) del músculo esquelético, causando una alteración profunda en la homeostasa de Ca2+, y caracterizando un estado hipermetabólico. RYR1, canales de liberación de Ca2+ del retículo sarcoplasmático, es la principal región de susceptibilidad a la HM. Varias mutaciones en el gen que codifica la proteína RYR1 han sido identificadas, pero otros genes pueden estar involucrados también. Actualmente, el método estándar para el diagnóstico de la sensibilidad a la HM es el test de contractura muscular para la exposición al halotano-cafeína (CHCT) y el único tratamiento es el uso de dantroleno. Sin embargo, con los avances en el campo de la genética molecular, un pleno entendimiento de la etiología de la enfermedad puede ser suministrado, favoreciendo así el desarrollo de un diagnóstico preciso, menos invasivo, con el test de ADN, y también proporcionar el desarrollo de nuevas estrategias terapéuticas para el tratamiento de la HM. Por eso, esta breve revisión intenta integrar los aspectos clínicos y moleculares de la HM, reuniendo informaciones para lograr una mejor comprensión de esa canalopatía.

Malignant hyperthermia: clinical and molecular aspects.

CONTENT: Malignant hyperthermia (MH) is a potentially lethal pharmacogenetic disorder that affects genetically predisposed individuals. It manifests in susceptible individuals in response to exposure to Inhalant anesthetics, depolarizing muscle relaxants or extreme physical activity in hot environments. During exposure to these triggering agents, there is a rapid and sustained increase of myoplasmic calcium (Ca(2+)) concentration induced by hyperactivation of ryanodine receptor of skeletal muscle (RyR1), causing a profound change in Ca(2+) homeostasis, featuring a hypermetabolic state. RyR1, Ca(2+) release channels of sarcoplasmic reticulum, is the primary locus for MH susceptibility. Several mutations in the gene encoding the protein RyR1 have been identified; however, other genes may be involved. Actually, the standard method for diagnosing MH susceptibility is the muscle contracture test for exposure to halothane-caffeine (CHCT) and the only treatment is the use of dantrolene. However, with advances in molecular genetics, a full understanding of the disease etiology may be provided, favoring the development of an accurate diagnosis, less invasive, with DNA test, and also will provide the development of new therapeutic strategies for treatment of MH. Thus, this brief review aims to integrate molecular and clinical aspects of MH, gathering input for a better understanding of this channelopathy.

Antidiarrheal activity of Solanum asterophorum in mice

Several species of Solanum are used in folk medicine to treat diarrhea. Therefore, the aim of this study was to investigate and compare possible antidiarrheal activity of methanol extracts from roots (Sast-MeOH R) and leaves (Sast-MeOH L) of Solanum asterophorum Mart., Solanaceae, in mice. Sast-MeOH R was shown to significantly and dose-relatedly inhibit the frequency of both solid (ED50 309.6±28.5 mg/kg) and liquid (ED50 152.1±32.5 mg/kg) stools. Conversely, Sast-MeOH L significantly inhibited solid stool frequency only when dosed at 500 and 750 mg/kg (48.7±7.4 and 42.3±9.8 percent, respectively), but also significantly and dose-relatedly inhibited liquid stools (ED50 268.4±35.2 mg/kg). Thus, Sast-MeOH R was twice as potent as Sast-MeOH L in diarrhea inhibition. Neither extracts (when dosed up to 500 mg/kg) inhibited intestinal transit. However, both extracts significantly and dose-relatedly inhibited intestinal fluids, and Sast-MeOH R (ED50 38.3±10.4 mg/kg) was again twice as potent as Sast-MeOH L (ED50 78.6±6.4 mg/kg). Results suggest that antidiarrheal effects of Sast-MeOH R and Sast-MeOH L involve changes on intestinal secretion. In addition, active metabolites with antidiarrheal activity may be more concentrated in the roots of this species. However further studies are needed to elucidate the action mechanism involved in this activity.