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Søren Grubb

@sorengrubb.bsky.social

1.6K followers 2.9K following 91 posts

Biologist👩‍🔬, physiologist🔬, electrophysiologist⚡, cardiovascular scientist❤️, neuroscientist🧠 #precapillarysphincters #microvasculature #meninges #neurovascularcoupling #pericytes #MICrONS #microglia #macrophages #wasteclearance #aging

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Søren Grubb @sorengrubb.bsky.social · Jun 10

🐭🧠 #PrecapillarySphincters (PS) at the #arteriole–#capillary junction rapidly dilate ~30% in seconds during #SensoryStimulation—regulating #capillary #BloodFlow dynamically. Here we investigated whether they protect downstream microvessels during abrupt #BloodPressure surges 🧪🧵

Showing how a precapillary sphincter dilates during high blood pressure

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Søren Grubb @sorengrubb.bsky.social · 12d

That reminds me of Thor fighting “midgårdsormen” the world serpent 🤣

Reposted by Søren Grubb

Ghouly Hoye 🇨🇦 👻 @hollyhoye.bsky.social · Sep 8

“Well I don’t like that study because it doesn't give me the result I want’

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Reposted by Søren Grubb

Hajime Hirase @hajimehirase.bsky.social · Jul 2

We are excited to report:
Cerebral blood flow is modulated by astrocytic cAMP elevation independently of IP3R2-mediated Ca2+ signaling in mice
Vittani et al. PNAS (2025)
pnas.org/doi/10.1073/...

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Søren Grubb @sorengrubb.bsky.social · Jun 24

The first Master’s student with me as main supervisor graduated today! I’m proud 🥹

Søren Grubb @sorengrubb.bsky.social · Jun 10

Thanks Amreen! ❤️

Søren Grubb @sorengrubb.bsky.social · Jun 10

🔗 Full Open Access manuscript: link.springer.com/article/10.1...
👇 Curious to hear more about #PrecapillarySphincters?
Check out these threads about the subject:
Characterization: x.com/SorenGrubb/s...
Ultrastructure: x.com/SorenGrubb/s...

Brain precapillary sphincters modulate myogenic tone in adult and aged mice - GeroScience

Brain precapillary sphincters, which are surrounded by contractile pericytes and are located at the junction of penetrating arterioles and first-order capillaries, can increase their diameter by ~ 30%...

link.springer.com

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Søren Grubb @sorengrubb.bsky.social · Jun 10

In older mice, where #MyogenicTone is weaker, #PrecapillarySphincters become even more critical barriers against #BloodPressure surges—compensating for #VascularStiffening and remodeling.

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Søren Grubb @sorengrubb.bsky.social · Jun 10

These changes suggest that #PrecapillarySphincters protect the capillaries 🛡️ by acting as a dynamic #resistance that regulates #capillary #BloodFlow and #BloodPressure.

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Søren Grubb @sorengrubb.bsky.social · Jun 10

Using #InVivo #VolumeImaging, we found #age related #vascular changes:
• ↑ #Tortuosity of #PenetratingArterioles
• ↓ #Arteriolar-capillary density
• ↑ #Capillaries at the venous end + #aneurysm-like bulbs downstream of #PrecapillarySphincters.

Søren Grubb @sorengrubb.bsky.social · Jun 10

By recording #cortical #angiograms during i.v. injection of FITC-dextran 🟢 in #adult and #old #NG2DsRed mice, we time-colored the #arterioles 🔴 and #venules 🔵. We found that #OldMice have less #collaterals and more #tortuous #PenetratingArterioles.

Søren Grubb @sorengrubb.bsky.social · Jun 10

After #LaserAblating pericytes around #PrecapillarySphincters, we observed impaired #MyogenicResponse and #NeurovascularCoupling—demonstrating #PrecapillarySphincter pericyte contractility is essential.

Figure showing how we used the two-photon laser to ablate the pericyte around the precapillary sphincter.

Søren Grubb @sorengrubb.bsky.social · Jun 10

#OldMice also showed decreased pulsations of microvessel diameters measured by transverse line scans, likely due to #VascularStiffening.

Figure showing how we measured microvascular diameters by transverse line scanning to assess the diameter pulsatility and the pulsatility of the centers of the vessels.

Søren Grubb @sorengrubb.bsky.social · Jun 10

In aged mice, the #MyogenicResponse was significantly blunted. This was shown by an increased #CorrelationCoefficient (CC) between #VascularDiameter and #BloodPressure

Figure showing blood pressure increase by the acute hypertensive challenge along with changed microvascular diameter in adult and old mice. CC= 0.13 for the adult mouse and 0.57 for the old mouse.

Søren Grubb @sorengrubb.bsky.social · Jun 10

We challenged mice with acute #BloodPressure spikes (~70% increase via angiotensin II). Result: both adult and #old mice got their #MyogenicResponse and #NeurovascularCoupling disrupted

Søren Grubb @sorengrubb.bsky.social · Jun 10

To visualize this, we used #InVivo #TwoPhotonMicroscopy in anesthetized adult and aged mice. Watch this video showing PS dilation in response to “SensoryStimulation! 🔬👇

Søren Grubb @sorengrubb.bsky.social · Jun 10

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Søren Grubb @sorengrubb.bsky.social · May 2

I was using indirect sunlight, but it seems like a better idea with an LED source. I was thinking of 3D printing a holder for my phone, so I don’t have to hold it at the right angle and distance to the eyepiece.

Søren Grubb @sorengrubb.bsky.social · May 2

Playing around with my 3yo daughter and an antique microscope. Looked at some #dandelion petals and a stamen using a Carl Zeiss P.A. 35 microscope using reflected light. 🧪

Dandelion petal under a Carl Zeiss P.A. 35 microscope

Dandelion stamen under a Carl Zeiss P.A. 35 microscope

Pollen on the dandelion stamen under a Carl Zeiss P.A. 35 microscope

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Søren Grubb @sorengrubb.bsky.social · May 2

@pkpd-babe.bsky.social Can I be added to the science post? My orcID: orcid.org/0000-0002-67...

ORCID

orcid.org

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Søren Grubb @sorengrubb.bsky.social · Apr 27

Small world. I studied biology with one of the researchers cited in that article. 😊

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Søren Grubb @sorengrubb.bsky.social · Mar 19

Amazing work out by Hirase Lab 🤩

Hajime Hirase @hajimehirase.bsky.social · Mar 19

Vittani, Lee, Wang, Hiraoka, et al.
KI mouse expressing red fluorescent blood
In situ SpyTag/Catcher attachment of biosensor
ECS SpyCatcher to capture BBB leak
doi.org/10.1101/2025...
We hope this method is useful to a wide range of the biology community.

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Søren Grubb @sorengrubb.bsky.social · Mar 18

Join our #PhDcourse on #openscience datasets and tools in #Neurophysiology!
We'll dive into #EM, #inVivo #physiology, behavioural analysis tools, and a talk on creating animations from open data! @quorumetrix.bsky.social
📢 Free for NorDoc PhD students, but open to all! Apply now!
lnkd.in/dU_fxqqu

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Reposted by Søren Grubb

Jon Cooper @joncooper-us.bsky.social · Feb 28

Pass it on.
#StandWithUkraine

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Reposted by Søren Grubb

Eric Topol @erictopol.bsky.social · Jan 12

Publications in the past week built substantially on our knowledge of the brain's waste disposal system—glymphatics—and the implications on sleep and brain aging.
Featuring exceptional work by Nedergaard Lab and @jonykipnis.bsky.social
erictopol.substack.com/p/our-sleep-... open-access

Our Sleep, Brain Aging, and Waste Clearance

How sleep prevents "dirty" brains that age faster

erictopol.substack.com

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Reposted by Søren Grubb

Asaf (Klaf) Weisman @asafklaf.bsky.social · Dec 25

🤘🏻The study I have been waiting for 30 years! Only Scandinavians can pull this out let alone publish it in a Scandinavian pain journal 🤘🏻
#painscience
#physio
#painresearch
#ignobel2025

www.degruyter.com/document/doi...

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