The biological function of hementin in the proboscis of the leech Haementeria ghilianii
Physiology published in Blood Coagul Fibrinolysis (1991)
Abstract
The giant Amazon leech Haementeria ghilianii feeds by inserting an exceedingly long tubular proboscis (up to 10 cm) deep into its mammalian host. The wound from its bite is not associated with prolonged bleeding because all antihaemostatic factors, including the fibrinogenolytic enzyme hementin, appear to be secreted exclusively into the lumen of the proboscis. It is in this narrow lumen that blood first comes into contact with hementin, the secretion of which is under neuronal control from the brain. During feeding, about 15 ml of blood are sucked through the proboscis at the rate of approximately 0.14 ml/min. A complete passage of blood takes less than 1 min, much faster than the approximately 6 min needed for coagulation (fibrin formation). Therefore, it is unlikely that hementin functions in the proboscis simply to prevent fibrin formation. Of greater risk is platelet aggregation which can occur within 1-2 min. The formation of a platelet-rich clot within the proboscis could make the proboscis non-functional. Hementin's unique ability to dissolve platelet-rich clots offers a way of restoring blood flow through the proboscis. Hementin is able to disaggregate platelets by breaking the fibrinogen crosslink between platelets. Hementin's unique cleavage site in the connector region of platelet-bound fibrinogen is thought to be a most effective mechanism for eliminating the crosslinking.
Abstract sourced from PubMed (NCBI) for the cited record. See the original publication for the authoritative version.
Resumen
Hementin in the giant Amazon leech's tubular proboscis functions primarily to disaggregate platelet clots — not to prevent fibrin formation per se — preserving proboscis patency during the ~1-minute blood passage.
Por qué esto importa para la hirudoterapia
Este estudio investiga la función biológica de la hementina en la probóscide de Haementeria ghilianii durante la alimentación, encontrando que la enzima se secreta bajo control neuronal exclusivamente hacia la luz de la probóscide, donde la sangre la contacta por primera vez. El resumen reporta que la sangre transita la probóscide en menos de un minuto—más rápido que los aproximadamente seis minutos necesarios para la formación de fibrina—lo que sugiere que la función principal de la hementina no es prevenir la coagulación, sino disolver coágulos ricos en plaquetas mediante la escisión de los enlaces cruzados de fibrinógeno entre plaquetas, para mantener la permeabilidad de la probóscide durante la alimentación. Esto es relevante para el dominio de ASH, ya que ilumina la ecología funcional de un anticoagulante de la sanguijuela en su contexto natural de alimentación. Sin embargo, el estudio concierne a la fisiología de alimentación de una especie distinta de Hirudo más que a la hirudoterapia clínica, lo que limita su relevancia práctica directa para la biología comparada de las sanguijuelas.
Citación
The biological function of hementin in the proboscis of the leech Haementeria ghilianii.
Sawyer RT, Jones CP, Munro R · Blood coagulation & fibrinolysis : an international journal in haemostasis and thrombosis, 1991
Contexto clínico relacionado
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Añadido a la biblioteca ASH: May 26, 2026 · Última actualización del sitio: 18 de junio de 2026