[Involvement of the Piezo1 and TRPV4 stretch-activated channels in pulmonary hypertension]. / Implication des canaux mécanosensibles Piezo1 et TRPV4 dans l'hypertension pulmonaire.

Pulmonary hypertension is a pulmonary circulation pathology characterized by remodelling and hyperreactivity of the pulmonary arteries. Vasodilatation/vasoconstriction balance is modified in favour of constriction via, among other things, the proliferation of smooth muscle cells and the development of endothelial dysfunction. In addition, the pulmonary arteries undergo modification of mechanical forces, inducing modified activation of stretch-activated channels (SAC) such as Piezo1 and TRPV4. These ionic channels are sensitive to stretch and their activation can induce various cellular physiological responses, which strongly contribute to development and continuation of the pathology.

Exposure of leopard frogs to a pesticide mixture affects life history characteristics of the lungworm Rhabdias ranae.

We tested the hypothesis that exposure of leopard frogs ( Rana pipiens) to agricultural pesticides can affect the infection dynamics of a common parasite of ranid frogs, the lungworm Rhabdias ranae. After a 21-day exposure to sublethal concentrations of a pesticide mixture composed of atrazine, metribuzin, aldicarb, endosulfan, lindane and dieldrin, or to control solutions (water, dimethyl sulfoxide), parasite-free juvenile frogs were challenged with 30 infective larvae of R. ranae. Approximately 75% of the larvae penetrated the skin and survived in both exposed and control animals, suggesting that pesticides did not influence host recognition or penetration components of the transmission process. Rather, we found that the migration of R. ranae was significantly accelerated in hosts exposed to the highest concentrations of pesticides, leading to the establishment of twice as many adult worms in the lungs of frogs 21 days post-infection. Pesticide treatment did not influence the growth of lungworms but our results indicate that they matured and reproduced earlier in pesticide-exposed frogs compared to control animals. Such alterations in life history characteristics that enhance parasite transmission may lead to an increase in virulence. Supporting evidence shows that certain components of the frog immune response were significantly suppressed after exposure to the pesticide mixture. This suggests that the immune system of anurans exerts a control over lungworm migration and maturation and that agricultural contaminants can interfere with these control mechanisms. Our results also contribute to the ongoing debate regarding the role that anthropogenic factors could play in the perplexing disease-related die-offs of amphibians observed in several parts of the world.