Blood pressure in the Greenland shark as estimated from ventral aortic elasticity

Abstract

We conducted inflations of freshly excised ventral aortas of the Greenland shark,, and used pressure-diameter data to estimate the point of transition from high to low compliance, which has been shown to occur at the mean blood pressure in other vertebrates including fishes. We also determined the pressure at which the modulus of elasticity of the aorta reached 0.4 MPa, as occurs at the compliance transition in other species. From these analyses, we predict the average ventral aortic blood pressure in to be about 2.3-2.8 kPa, much lower than reported for other sharks. Our results support the idea that this species is slow moving and has a relatively low aerobic metabolism. Histological investigation of the ventral aorta shows that elastic fibres are present in relatively low abundance and loosely connected, consistent with this aorta having high compliance at a relatively low blood pressure.

Advancing Research for the Management of Long-Lived Species: A Case Study on the Greenland Shark

“…Further evidence of interspecies haplotype sharing has been reported for several juvenile Greenland sharks from the high Arctic that were found to be carrying S. pacificus mtDNA haplotypes (Hussey et al, 2015a). More recently, a full mtDNA genome sequenced with phylogenetic reconstruction placed the Greenland shark and Pacific sleeper shark as sister species with respect to other major shark orders (Santaquiteria et al, 2017). By calibrating the mitogenomic phylogenetic reconstruction with fossil records and geological events, the speciation time of these two species was confirmed to be 3.5 million years ago (mya) (Santaquiteria, 2016;in agreement with Murray et al, 2008).…”

“…In heart strips that appeared to be contracting normally, a single contraction/relaxation cycle (i.e., a twitch) required 3-5 s to complete at 5 • C, suggesting that maximal heart rate ranges from 12 to 20 beats/min (in agreement with Shiels et al, 2018). While blood pressure in Greenland sharks has never been directly measured, it has been estimated by analyzing the relative amounts of elastin and collagen in the wall of the ventral aorta and measuring its compliance characteristics over a range of pressures (Shadwick et al, 2018). These data suggest that the Greenland shark's average blood pressure is approximately 2.3-2.8 kPa, much lower than other slow swimming sharks, such as the epaulet shark, Hemiscyllium ocellatum (3.9 kPa), or catshark, Scyliorhinus canicula (5.3 kPa), where it has been directly measured (Taylor et al, 1977;Speers-Roesch et al, 2012).…”

Neuropathological evaluation of a vertebrate brain aged ~ 245 years

“…trimethylamine that might be neuroprotective. It is further suggested that Greenland sharks feature a relatively low blood pressure compared to other sharks [18] that might reduce the risk of hypertension-related CNS damage such as stroke or cognitive decline [5]. Up to now, information about genetics from Greenland sharks are largely missing [4,17].…”