Rete Mirabile of Dolphin: Its Pressure-Damping Effect on Cerebral Circulation

Nagel, Eugene L.; Morgane, P. J.; McFarland, W. L.; Galllano, R. E.

doi:10.1126/science.161.3844.898

Cited by 60 publications

(32 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Moreover, NO, located in sympathetic nerves, can be released as a co-transmitter in the peripheral autonomic system and induces vasodilator effects (Toda and Okamura, 2003). It is well known that Cetaceans have morphophysiological features that permit them to live in aquatic environment (Nagel et al, 1968;Vogl and Fisher, 1981;Ochrymowych and Lambertsen, 1984;Melnikov, 1997;Bombardi et al, 2010Bombardi et al, , 2011. In particular, during diving, blood is shifted to the huge retia mirabilia, to allow physiological distribution of fluids, permit thoracic compression at depth, heat the spinal cord, and regulate the oxygenation of the brain during the long breath-holding dives.…”

Section: Discussionmentioning

confidence: 99%

Nitrergic Neurons in the Spinal Cord of the Bottlenose Dolphin (Tursiops truncatus)

Bombardi

Grandis

Gardini

et al. 2013

The Anatomical Record

View full text Add to dashboard Cite

Nitric oxide (NO) is a freely diffusible gaseous neurotransmitter generated by a selected population of neurons and acts as a paracrine molecule in the nervous system. NO is synthesized from L-arginine by means of the neuronal nitric oxide synthase (nNOS), an enzyme requiring nicotine adenine dinucleotide phosphate (NADPH) as cofactor. In this study, we used histochemical and immunohistochemical techniques to investigate the distribution of NADPH-diaphorase (NADPH-d) and nNOS in the spinal cord of the bottlenose dolphin (Tursiops truncatus). Cells with a fusiform-shaped somata were numerous in the laminae I and II. The intermediolateral horn showed darkly-stained cells with a multipolar morphology. Neurons with a multipolar or fusiform morphology were observed in the ventral horn. Multipolar and fusiform neurons were the most common cell types in lamina X. Nitrergic fibers were numerous especially in the dorsal and intermediolateral horns. The presence of nitrergic cells and fibers in different laminae of the spinal cord suggests that NO may be involved in spinal sensory and visceral circuitries, and potentially contribute to the regulation of the complex retia mirabilia.

show abstract

Section: Discussionmentioning

confidence: 99%

Nitrergic Neurons in the Spinal Cord of the Bottlenose Dolphin (Tursiops truncatus)

Bombardi

Grandis

Gardini

et al. 2013

The Anatomical Record

View full text Add to dashboard Cite

show abstract

“…Direct neural control of retial arteries would allow rapid blood redistribution (Nagel et al, 1968), but although ample innervation runs in close proximity to dolphin and fin whale rete (Nagel et al, 1968;Ommanney, 1932), direct adrenergic connections have been shown to be poor in the rete of the narwhal (Vogl et al, 1981). Pfeiffer et al (Pfeiffer and Kinkead, 1990), studying nonthoracic retial arteries from the bowhead whale, Balaena mysticetus, came to a similar conclusion based on a number of morphological features including the observation of ganglia-like complexes in the media, but no diffuse neurons.…”

Section: Model Predictions Of Thoracic Pressurementioning

confidence: 99%

Cardiovascular design in fin whales: high-stiffness arteries protect against adverse pressure gradients at depth

Lillie

Piscitelli

Vogl

et al. 2013

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARYFin whales have an incompliant aorta, which, we hypothesize, represents an adaptation to large, depth-induced variations in arterial transmural pressures. We hypothesize these variations arise from a limited ability of tissues to respond to rapid changes in ambient ocean pressures during a dive. We tested this hypothesis by measuring arterial mechanics experimentally and modelling arterial transmural pressures mathematically. The mechanical properties of mammalian arteries reflect the physiological loads they experience, so we examined a wide range of fin whale arteries. All arteries had abundant adventitial collagen that was usually recruited at very low stretches and inflation pressures (2-3kPa), making arterial diameter largely independent of transmural pressure. Arteries withstood significant negative transmural pressures (−7 to −50kPa) before collapsing. Collapse was resisted by recruitment of adventitial collagen at very low stretches. These findings are compatible with the hypothesis of depth-induced variation of arterial transmural pressure. Because transmural pressures depend on thoracic pressures, we modelled the thorax of a diving fin whale to assess the likelihood of significant variation in transmural pressures. The model predicted that deformation of the thorax body wall and diaphragm could not always equalize thoracic and ambient pressures because of asymmetrical conditions on dive descent and ascent. Redistribution of blood could partially compensate for asymmetrical conditions, but inertial and viscoelastic lag necessarily limits tissue response rates. Without pressure equilibrium, particularly when ambient pressures change rapidly, internal pressure gradients will develop and expose arteries to transient pressure fluctuations, but with minimal hemodynamic consequence due to their low compliance.

show abstract

“…In our research, however, the high percentage ($50%) of SP-IR neurons reflects a previously unreported situation (Lawson, 1992;Willis and Coggeshall, 2004), possibly typical of the dolphin. Cetaceans have unique morphophysiological vascular features that reflect an extreme adaptation to the aquatic environment (Nagel et al, 1968;Vogl and Fisher, 1981;Ochrymowych and Lambertsen, 1984;Melnikov, 1997;Sedmera et al, 2003). In particular, the vascular system of cetaceans shows numerous retia mirabilia.…”

Section: Discussionmentioning

confidence: 99%

Immunohistochemical Localization of Substance P And Cholecystokinin in the Dorsal Root Ganglia and Spinal Cord of the Bottlenose Dolphin (Tursiops truncatus)

Bombardi

Grandis

Nenzi

et al. 2010

The Anatomical Record

View full text Add to dashboard Cite

The presence of substance P (SP) and cholecystokinin (CCK) immunoreactive neurons was examined in the bottlenose dolphin dorsal root ganglia (DRGs) and spinal cord by immunohistochemical techniques. SPpositive and CCK-immunoreactive neurons were respectively $50% and 1% of the total number of ganglion cells examined and especially belonged to small and medium-sized cell populations. Using double labeling techniques we observed that SP-and CCK-immunoreactivity coexisted in a very low number of primary afferent neurons (2.7%). Few SPimmunoreactive (IR) neurons (2.7%) were also CCK-positive. On the contrary, 65% of CCK-immunoreactive neurons contained SP. Interestingly, we observed CCK-immunoreactive satellite glial cells located around large cell class somata. Virtually no SP-IR and CCK-positive neurons were surrounded by peripheral CCK-immunoreactive satellite glial cells. The SP-IR and CCK-positive nerve fibers were particularly conspicuous in the superficial layers of the spinal cord. The present study indicates that SP and CCK only partially overlap in the thoracic, lumbar, and caudal DRGs of the bottlenose dolphin, suggesting that the majority of SP-IR ganglion neurons are lacking in CCK-immunoreactivity. The role of SPcontaining DRG neurons is discussed also in relation to the huge vascular spinal retia mirabilia typical of cetaceans. Anat Rec, 293:477-484, 2010. V V C 2010 Wiley-Liss, Inc.

show abstract

Rete Mirabile of Dolphin: Its Pressure-Damping Effect on Cerebral Circulation

Cited by 60 publications

References 7 publications

Nitrergic Neurons in the Spinal Cord of the Bottlenose Dolphin (Tursiops truncatus)

Nitrergic Neurons in the Spinal Cord of the Bottlenose Dolphin (Tursiops truncatus)

Cardiovascular design in fin whales: high-stiffness arteries protect against adverse pressure gradients at depth

Immunohistochemical Localization of Substance P And Cholecystokinin in the Dorsal Root Ganglia and Spinal Cord of the Bottlenose Dolphin (Tursiops truncatus)

Contact Info

Product

Resources

About