Sucrose is a gap junction permeant.
“However, recent X-ray diffraction data show that the channels of crystalline gap junctions (typical of uncoupled cells) are indeed closed, because they are inaccessible to sucrose (a gap junction permeant).”
Gap junction structure and cell-to-cell coupling regulation: is there a calmodulin involvement?
“In endothelial cell culture, simple sugars effectively impair mechanosensor proteins.”
Endothelial mechanotransduction proteins and vascular function are altered by dietary sucrose supplementation in healthy young male subjects - PMC
“Hypertonic sucrose solution applied to an arteriole segment along the apparent conducting pathway attenuated propagation significantly, which is consistent with its reported effect to decouple gap junctions between cells.”
“It is suggested that the opening of KATP channels in vascular endothelium and subsequent hyperpolarization of that cell type mediate coronary microvascular dilation in response to hyperosmolarity.”
Propagation of vasodilation in resistance vessels of the hamster: development and review of a working hypothesis
“In this regard, porcine coronary arterioles (81 +/- 2 microns) were isolated, cannulated, and pressurized for in vitro study. Hyperosmolarity (300-345 mosM) was produced by adding D-glucose or D-sucrose to the extravascular solution. After the arterioles developed a stable vascular tone, a graded vasodilation was observed when glucose or sucrose was incrementally administered.”
Endothelial ATP-sensitive potassium channels mediate coronary microvascular dilation to hyperosmolarity
“Direct intercellular communication via gap junctions is critical in the control and coordination of vascular function. In the cardiovascular system, gap junctions are made up of one or more of four connexin proteins: Cx37, Cx40, Cx43, and Cx45.”
“Direct electrical communication between endothelial cells and vascular smooth muscle cells via gap junctions is thought to play a relevant role in the control of vasomotor tone, providing the signaling pathway known as endothelium-derived hyperpolarizing factor (EDHF).”
This review paper mentioned glucose incubation influence on expression of Cx43, but that’s probably not relevant to this. I really only am including this paper because it describes in detail different aspects of the connexins, their structure, etc..
https://www.lie bertpub.com/doi … 9/ars.2008.2117
“In response to vasoactive factors and to shear stress elicited by blood flow, the endothelium secretes vasodilating or vasocontracting autacoids, which adjust the contractile state of the smooth muscle. In endothelial sensing of shear stress, the osmo- and mechanosensitive Ca2+-permeable TRPV4 channel has been proposed to be candidate mechanosensor.”
https://journal s.plos.org/plos … al.pone.0000827
“It is interesting to note that shear
stress upregulates the expression of Cx43 in cultured endo-
thelial cells (6, 38) and in the endothelium of rat cardiac
valves (93), which is consistent with the idea that Cx43 is in-
volved in the sensitivity to mechanical stimuli.”
https://www.lie bertpub.com/doi … 9/ars.2008.2117
“The sucrose gap technique is used to create a conduction block in nerve or muscle fibers. A high concentration of sucrose is applied to the extracellular space, which prevents the correct opening and closing of sodium and potassium channels, increasing resistance between two groups of cells.”
https://en.wiki … iki/Sucrose_gap
Discussion:
So what is sucrose doing when used in pumping?
I’ve tried it once for about 40 minutes, I didn’t notice an increase in size. I’ll try it again later.
I noticed altered sensation, which I’m not certain was real or just a placebo effect.
In summary, what are the potential known mechanisms?
Nerve signal disruption, vasodilation can be caused via neuron. You can cause priapism by a sympathetic nerve block. There are also drug abuse complications that “deplete nerves” and cause priapism, sometimes resulting in the need for amputation. From what I understand about this, the sympathetic nerves within the penis suppress vasodilation, while the parasympathetic nerves can trigger vasodilation. I guess I should read more into this subject and overcome my disinterest in the nervous system. Please don’t get any ideas, these are the kinds of things I’m hesitant to mention out of fear for people’s safety.
A nice paper on “Physiology of Penile Erection and Pathophysiology of Erectile Dysfunction” talking about nerves.
https://www.ncb i.nlm.nih.gov/p … les/PMC1351051/
I don’t know why sucrose would block sympathetic nerves that constrict arteries, but not parasympathetic and somatic nerves that dilate arteries. Perhaps sucrose dilates via endothelial gap junction effects, so it doesn’t matter what the nerves are doing? Perhaps the distribution of sucrose is different for different regions. I find it hard to believe sucrose could penetrate to the dorsal nerve cord in sufficient quantity to do anything, but could it enter the mucosa of the glans to effect endothelial cells? Most likely, but I don’t know by how much or for how long.
Priapism following a lumbar sympathetic nerve block
Endothelial gap junction disruption, depending on the connexins influenced, or the combination of connexins in a hemichannel, could do different things, vasodilate or constrict. Studies say it causes artery dilation, which is kind of perplexing because if sucrose is disconnecting gap junctions, how does the upstream artery know to dilate? Maybe just through the shear stress of increased blood flow? Maybe they dilate in the absence of transmission?
Sucrose apparently is a permeant that enters gap junctions, maybe they enter alone, maybe they chaperone something else, maybe they leave the junction open so things can leak out. Needs more clarification.
Sucrose could also just have an effect due to osmotic influence on arteries.
It’s an assumption it works on arteries, it might work on veins, or it might work on both. There’s also the mechanosensory aspect of it, maybe it’s an inhibitor of the dreaded contraction response to high forces.
I’m going to keep reading and thinking about this, keeping track of links slows me down quite a bit. I still haven’t verified this phenomenon even occurs, so all this speculation about mechanisms might be for nothing. I’m sure my interest will be peaked again later if I can verify the phenomenon.
This is not proof read, it’s just some notes.