Björn Folkow

Björn Folkow (/ˈbjɜːrn ˈfɒlkɒv/; October 13, 1921 - July 23. 2012) was a Swedish physiologist. He was professor in physiology at the University of Gothenburg between 1961 and 1987 and a member of the Royal Swedish Academy of Sciences.

B Folkow 1991

Biography

Björn Folkow was born in Halmstad, Sweden. He studied medicine at Lund University where he continued with doctoral studies in physiology. He defended his thesis on May 9, 1949.[1] Soon thereafter he became associate professor ('laborator') at the new Department of Physiology at the University of Gothenburg. He became full professor in 1961[2] and remained there until his retirement in 1987. Even after retirement he continued being active in the department until shortly before his death in 2012.[3]

Folkow was a member of the Royal Swedish Academy of Sciences and member of the Danish and Russian Academies of Sciences.[3] The European Society of Hypertension established the Björn Folkow Award and Lecture in 1989.[4]

Scientific activity

Folkow published more than 400 scientific papers, covering most areas of cardiovascular physiology. He was an international authority in the field of high blood pressure.[5] His main contributions arguably are found in the following areas:

  • The myogenic response of blood vessels. In 1902 Bayliss [6] described that many blood vessels respond to an elevation of transmural pressure by constriction, finally reaching a diameter that is smaller than the initial diameter at the lower pressure. This observation, which had not received much attention at the time, was studied by Folkow as part of his thesis work and subsequently for more than a decade. He described this mechanism as an essential element in vascular control. This is now well-established knowledge in cardiovascular physiology.
  • The structural adaptation of blood vessels to elevated blood pressure. Folkow and coworkers studied the blood flow in the forearm in persons with high blood pressure, finding an elevated resistance to flow even in situations when the blood vessels would be fully dilated.[7] This indicated a structural adaptation of the blood vessels to a state with smaller lumen diameter but thicker wall (what now is termed remodelling[8]). This confers to the vessel wall what corresponds to a longer lever, enabling them to contract against higher pressures. This can be seen as the beginning of a vicious circle, where an elevation of pressure causes remodelling that promotes further pressure elevation. Folkow's description of these vascular alterations[9] has since been verified in a large number of studies.
  • The role of the central nervous system in cardiovascular control. Possibly as a consequence of Folkow's interest in the interplay between body and mind he became interested in central nervous control of the cardiovascular system.[10] He particularly pointed to the role of the defence-alarm reaction (the fight-or-flight response) in everyday blood-pressure control. His opinion was that individuals with a tendency to react more strongly with this response tend to develop higher blood pressure, since they more often get blood pressure elevation in response to common stressors. Even though the kidney is important for blood pressure control, he viewed it as subordinate to the brain.
  • The function of the sympathetic nerve terminals. The sympathetic nervous system has a central role in blood pressure control. It thus attracted Folkow's attention early on,[10] in particular following the mapping of this system.[3] Combining quantification of the density of adrenergic varicosities in the vascular wall with estimates of noradrenaline release indicated that on average only a few per cent of the transmitter content of a synaptic vesicle was released from a given nerve terminal by an action potential in the nerve.[11] It has since been found that transmitter release from a varicosity is intermittent,[12] but whether all or only part of the vesicle's contents is released is still a matter of debate.[13][14][15]
  • The physiology of aging. Partly because of his contacts with the professor of geriatrics in Gothenburg, Alvar Svanborg, Folkow acquired an interest for the implications of physiological aging in cardiovascular control. This collaboration resulted in a major review article in this field.[16]

Textbook
  • Circulation[17] This textbook was written by Folkow in collaboration with Eric Neil. It is a thorough description of the essential concepts in this area, and large parts of it remain relevant even today, although for obvious reasons more modern aspects are lacking. A follow-up was planned in the eighties in collaboration with Paul Korner, but due to differences in opinion on several aspects Folkow withdrew from the collaboration to save their friendship.

References
  1. Folkow, Björn (1949). Observationer rörande nervösa, kemiska och mekaniska faktorers betydelse för regleringen av de små blodkärlens tonus. Lund: Carl Bloms Boktryckeri. pp. 1–15.
  2. "Sveriges statskalender 1984". Retrieved January 1, 2018.
  3. Nilsson, H; Lundgren, O (2012). "Björn Folkow (1921-2012)". Acta Physiol (Oxf). 206 (4): 251–254. doi:10.1111/apha.12031. PMID 23110468.
  4. "European Society of Hypertension in Brief". Retrieved January 1, 2018.
  5. DiBona, GF; Mark, AL (2013). "Björn Folkow". Hypertension. 61 (1): 4. doi:10.1161/HYPERTENSIONAHA.111.00239. PMID 23362518.
  6. Bayliss, WA (1902). "On the local reactions of the arterial wall to changes of internal pressure". J Physiol. 28 (3): 220–231. doi:10.1113/jphysiol.1902.sp000911. PMC 1540533. PMID 16992618.
  7. Folkow, B; Grimby, G; Thulesius, O (1958). "Adaptive structural changes of the vascular walls in hypertension and their relation to the control of the peripheral resistance". Acta Physiol Scand. 44 (3–4): 255–272. doi:10.1111/j.1748-1716.1958.tb01626.x. PMID 13617022.
  8. Mulvany, MJ (1999). "Vascular remodelling of resistance vessels: can we define this?". Cardiovasc Res. 41 (1): 9–13. doi:10.1016/S0008-6363(98)00289-2. PMID 10325946.
  9. Folkow, B (1982). "Physiological aspects of primary hypertension". Physiol Rev. 62 (2): 347–504. doi:10.1152/physrev.1982.62.2.347. PMID 6461865.
  10. Folkow, B (1955). "Nervous control of the blood vessels". Physiol Rev. 35 (3): 629–663. doi:10.1152/physrev.1955.35.3.629. PMID 13245427.
  11. Folkow, B; Häggendal, J; Lisander, B (1967). "Extent of release and elimination of noradrenaline at peripheral adrenergic nerve terminals". Acta Physiol Scand. suppl. 307: 1–38. doi:10.1111/apha.1967.72.issue-s307. PMID 4297559.
  12. Brock, JA; Cunnane, TC (1987). "Relationship between the nerve action potential and transmitter release from sympathetic postganglionic nerve terminals". Nature. 326 (6113): 605–607. Bibcode:1987Natur.326..605B. doi:10.1038/326605a0. PMID 2882426. S2CID 4303337.
  13. Folkow, B; Nilsson, H (1997). "Transmitter Release at Adrenergic Nerve Endings: Total Exocytosis or Fractional Release?". News Physiol. Sci. 12: 32–36. doi:10.1152/physiologyonline.1997.12.1.32.
  14. Jena, BP (2015). "'Porosome' discovered nearly 20 years ago provides molecular insights into the kiss-and-run mechanism of cell secretion". J Cell Mol Med. 19 (7): 1427–1440. doi:10.1111/jcmm.12598. PMC 4511343. PMID 26033351.
  15. Omiatek, DM; Dong, Y; Heien, ML; Ewing, AG (2010). "Only a fraction of quantal content is released during exocytosis as revealed by electrochemical cytometry of secretory vesicles". ACS Chem Neurosci. 1 (3): 234–245. doi:10.1021/cn900040e. PMC 2847285. PMID 20368748.
  16. Folkow, B; Svanborg, A (1993). "Physiology of cardiovascular aging". Physiol Rev. 73 (4): 725–764. doi:10.1152/physrev.1954.34.3.608. PMID 13185757.
  17. Folkow, B; Neil, E (1971). Circulation. New York, London, Toronto: Oxford University Press. pp. 1–593.
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