B3.2-1 Transport in animals The circulatory system

International Scholarly Research Notices, 2014

Present review paper highlights role of BBB in endothelial transport of various substances into the brain. More specifically, permeability functions of BBB in transendothelial transport of various substances such as metabolic fuels, ethanol, amino acids, proteins, peptides, lipids, vitamins, neurotransmitters, monocarbxylic acids, gases, water, and minerals in the peripheral circulation and into the brain have been widely explained. In addition, roles of various receptors, ATP powered pumps, channels, and transporters in transport of vital molecules in maintenance of homeostasis and normal body functions have been described in detail. Major role of integral membrane proteins, carriers, or transporters in drug transport is highlighted. Both diffusion and carrier mediated transport mechanisms which facilitate molecular trafficking through transcellular route to maintain influx and outflux of important nutrients and metabolic substances are elucidated. Present review paper aims to emph...

Comprehensive Physiology, 2016

Mass transport can be generally defined as movement of material matter. The circulatory system then is a biological example given its role in the movement in transporting gases, nutrients, wastes, and chemical signals. Comparative physiology has a long history of providing new insights and advancing our understanding of circulatory mass transport across a wide array of circulatory systems. Here we focus on circulatory function of nonmodel species. Invertebrates possess diverse convection systems; that at the most complex generate pressures and perform at a level comparable to vertebrates. Many invertebrates actively modulate cardiovascular function using neuronal, neurohormonal, and skeletal muscle activity. In vertebrates, our understanding of cardiac morphology, cardiomyocyte function, and contractile protein regulation by Ca 2+ highlights a high degree of conservation, but differences between species exist and are coupled to variable environments and body temperatures. Key regulators of vertebrate cardiac function and systemic blood pressure include the autonomic nervous system, hormones, and ventricular filling. Further chemical factors regulating cardiovascular function include adenosine, natriuretic peptides, arginine vasotocin, endothelin 1, bradykinin, histamine, nitric oxide, and hydrogen sulfide, to name but a few. Diverse vascular morphologies and the regulation of blood flow in the coronary and cerebral circulations are also apparent in nonmammalian species. Dynamic adjustments of cardiovascular function are associated with exercise on land, flying at high altitude, prolonged dives by marine mammals, and unique morphology, such as the giraffe. Future studies should address limits of gas exchange and convective transport, the evolution of high arterial pressure across diverse taxa, and the importance of the cardiovascular system adaptations to extreme environments.

Federation proceedings

Capillary-tissue exchange of inert hydrophilic solutes in the heart occurs through aqueous channels, the clefts between endothelial cells (ECs). For adenosine (and other vasoactive agents and substrates), there is also transport across the plasmalemma of the ECs. The multiple-indicator dilution technique comparing tracer adenosine flux with that of 9-β-Darabinofuranosylhypoxanthine (an analog that is not transported by the nucleoside carrier) can be used to estimate the conductance of the facilitated transport mechanism, which is equivalent to a permeability-surface area product. Analysis by using a model of exchanges among capillary, EC, interstitium, and myocardial cells suggests that the abluminal surface of the ECs is also highly permeable to adenosine. The inference is that ECs may be an important component of a system for adenosine exchange and regulation in the heart.

Frontiers in Pharmacology, 2024

The emergence of the plasma membrane marked a pivotal milestone in the progression of cellular life. Alongside safeguarding genetic material, this structural development introduced a challenge: enabling the exchange of various substances-such as nutrients, foreign compounds (xenobiotics), hormones and metabolic by-products-between the interior and exterior compartments of the cell. To tackle this issue, the plasma membrane advanced through the integration of transport proteins facilitating the movement of charged hydrophilic elements across this membrane. Transport proteins, constituting the most extensive family of membrane proteins within the human organism, are present in every cell. Consequently, these transporters hold profound significance in cellular physiology and exhibit a high degree of preservation throughout evolutionary processes. Across diverse organs, an array of transporters is integral, serving as fundamental determinants of their respective functionalities. Transporters play a pivotal role in facilitating the absorption, distribution, metabolism, elimination, and toxicity (ADMET) of pharmaceutical compounds, influencing drug's efficacy and safety. Due to their involvement in these critical processes, transporters provide a pathway to explore crucial realms of physiology, toxicology, and pharmacology. Their significance extends as they offer insights into the intricate mechanisms governing drug interactions and responses within the body. The TransportDays in Greifswald, Germany, place a spotlight on critical facets of transporter functionality. This event is tailored for and orchestrated by scientists passionate about the fields of physiology, pharmacology, and structural biology concerning cell membrane channels and transporters. These belong mostly to the ATP-Binding Cassette (ABC) to the solute carrier (SLC) transporter family . Originally conceived by Prof. Gerhard Burckhardt to honor the legacy of Prof. Karl J. Ullrich, a trailblazer in renal transport physiology and the former director of the Max-Planck-Institute for Biophysics in Frankfurt , the TransportDays initially drew participants primarily influenced by Prof.

AJP: Heart and Circulatory Physiology, 2006

This paper measures the filtration flows through the walls of the rat aorta, pulmonary artery (PA) and inferior vena cava (IVC), vessels with very different susceptibilities to atherosclerosis, as a function of transmural pressure P, both with intact and denuded endothelium on the same vessel. Aortic hydraulic conductivity Lp is high at 60 mmHg, drops by ~40% by 100 mmHg and is pressure-independent to 140 mmHg. The trends are similar in the PA and IVC, dropping 42% from 10-40 mmHg and flat to 100 mmHg (PA) and dropping 33% from 10-20 mmHg and essentially flat to 60 mmHg (IVC). Endothelial removal renders Lp( P) flat; it increases Lp of the aorta by ~75%, doubles Lp of the PA and quadruples Lp of the IVC. The specific resistance (1/Lp) of the aortic endothelium is ~47% of the total resistance, i.e., the endothelium takes up ~47% of the transmural pressure drop at 100 mmHg. The PA value is 55% above 40 mmHg and the IVC value is 23% at 10 mmHg. Lps of the intact aorta, PA and IVC have magnitudes of 10 -8 , 10 -7 and 5x10 -7 cm/(s mmHg) and wall thicknesses 145.8±9.3, 78.9±3.3 and 66.1±4.1 (mean ± SD) µm. These data are consistent with the differing wall structures of the three vessels. The rat aortic Lp data are quantitatively consistent with rabbit Lp( P) (Tedgui & Lever, AJP, 247, H784-91, 1984; Baldwin & Wilson, AJP, 264, H26-32, 1993), suggesting that intimal compression under pressure loading may also play a role in Lp( P) in these other vessels. Despite experiencing very different driving transmural pressures, these three vessels' nominal transmural water fluxes are very similar, and therefore cannot alone account for their different disease susceptibilities. The differing fates of macromolecular tracers convected by these water fluxes into these vessels' walls may address this question.

2015

2000

This paper measures the filtration flows through the walls of the rat aorta, pulmonary artery (PA) and inferior vena cava (IVC), vessels with very different susceptibilities to athero- sclerosis, as a function of transmural pressureP, both with intact and denuded endothelium on the same vessel. Aortic hydraulic conductivity Lp is high at 60 mmHg, drops by ~40% by 100 mmHg

American Journal of Physiology-heart and Circulatory Physiology, 2012

Zeng Z, Jan KM, Rumschitzki DS. A theory for water and macromolecular transport in the pulmonary artery wall with a detailed comparison to the aorta.

Principles of Medical Biochemistry, 2012

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Journal of Controlled Release, 1987

The role molecular structure in determining transport across biological membranes is presented in terms of partitioning, molecular size, and solubility. Simple models are given as a starting point for a predictive scheme.