Deciphering function of the pulmonary arterial sphincters in loggerhead sea turtles (Caretta caretta) [RESEARCH ARTICLE]

Daniel Garcia-Parraga, Teresa Lorenzo, Tobias Wang, Jose Luis Ortiz, Joaquin Ortega, Jose Luis Crespo-Picazo, Julio Cortijo, and Andreas Fahlman To provide new insight to the pathophysiological mechanisms underlying gas emboli (GE) in bycaught loggerhead sea turtles (Caretta caretta), the present study investigated the vasoactive characteristics of the pulmonary and systemic arteries, and the lung parenchyma (LP). Tissues were opportunistically excised from recently dead animals for in vitro studies of vasoactive responses to four different neurotransmitters: acetylcholine (ACh, parasympathetic), serotonin (5HT), epinephrine (Epi, sympathetic) and histamine. The significant amount of smooth muscle in the LP contracted in response to ACh, Epi and histamine. The intrapulmonary and systemic arteries contracted under both parasympathetic and sympathetic stimulation and when exposed to 5HT. However, proximal extrapulmonary arterial (PEPA) sections contracted in response to ACh and 5HT, while Epi caused relaxation. In sea turtles, the relaxation in the pulmonary artery was particularly pronounced at the level of the pulmonary artery sphincter (PASp) where the vessel wall was highly muscular. For comparison, we also studied tissue response in freshwater sliders turtles (Trachemys scripta elegans). Both PEPA and LP from freshwater sliders contracted in response to 5HT, ACh and conversely to sea turtles, also under Epi. We propose that in sea turtles the dive response (parasympathetic...
Source: Journal of Experimental Biology - Category: Biology Authors: Tags: RESEARCH ARTICLE Source Type: research