Dr. Kumar’s Take
This is a laboratory study in heart muscle cells, not a study of people. The researchers grew neonatal rat ventricular myocytes and exposed them to nicotine, then tracked what happened inside the mitochondria. Nicotine raised mitochondria-derived superoxide, dropped the mitochondrial membrane potential, and jammed the PINK1/Parkin recycling pathway that normally clears damaged mitochondria. With the cleanup blocked, the mitochondrial network tipped toward fragmentation and the cells went into apoptosis. As a neurosurgeon I care about this because the same nicotine that patients think of as a harmless focus aid is acting directly on cardiac muscle cell machinery in the dish, independent of smoke.
What to do about it: if you use nicotine, make a plan to taper and quit. Support your mitochondria with the basics that lower oxidative stress: regular exercise, adequate sleep, and a diet rich in colorful plants and omega-3 fats. If you are using nicotine to focus, swap to safer strategies below.
Key Takeaways
✔ This was a cell study in rat heart muscle cells, neonatal rat ventricular myocytes, not a human trial and not neurons.
✔ Nicotine increased mitochondria-derived superoxide and lowered mitochondrial membrane potential.
✔ Nicotine impaired PINK1/Parkin-mediated mitophagic flux, the pathway that clears damaged mitochondria.
✔ Mitochondria fragmented. Nicotine promoted Drp1-mediated fission and suppressed mitofusin-mediated fusion, and excessive fission led to apoptosis.
✔ Blocking Drp1 with Mdivi-1 reduced the apoptosis, which points to fission as the step that kills the cell.
✔ Translation: nicotine itself, not just smoke, stresses the energy machinery of heart muscle cells in the lab.
Actionable Tip
If you currently use nicotine, set a quit plan that combines behavioral coaching with first-line medications such as varenicline or combination nicotine replacement, under medical guidance. Pair it with daily brisk activity, a full night of sleep, and a whole food diet to support mitochondrial health during withdrawal.
Study Summary
Topic: What does nicotine do to mitophagy, mitochondrial dynamics, and apoptosis in cardiomyocytes, and through what mechanism?
Why it matters: nicotine, in traditional cigarettes, hookahs, and e-cigarettes, is a risk factor for cardiovascular disease. It promotes hypertension-related vascular endothelial dysfunction, oxidative stress, inflammation, fibrosis, and apoptosis, and it affects the structure and function of the heart. The mechanism behind nicotine-induced cardiomyocyte injury has not been clear.
What the authors found:
- Nicotine exposure increased mitochondria-derived superoxide production and decreased mitochondrial membrane potential in the cells.
- Nicotine impaired PINK1/Parkin-mediated mitophagic flux.
- Nicotine promoted Drp1-mediated mitochondrial fission and suppressed mitofusin-mediated fusion. The same pattern appeared in the bafilomycin A1-treated group, which the authors say suggests mitophagic flux impairment may contribute to Drp1-mediated fission.
- Excessive fission contributed to apoptosis, and the Drp1 inhibitor Mdivi-1 alleviated it.
- The enzyme activity of cathepsin L (CTSL) fell in lysosomes after nicotine, alongside the cathepsin B drop the same group had reported previously. The authors treat the CTSL loss as the main reason mitophagic flux stalls.
Study Design and Methods (Plain Language)
- Model: an in vitro cell study in neonatal rat ventricular myocytes, that is, rat heart muscle cells in culture.
- Exposure: the cultured cardiomyocytes were treated with nicotine, and the researchers measured mitochondria-derived superoxide, mitochondrial membrane potential, mitophagic flux through PINK1/Parkin, markers of mitochondrial fission and fusion, lysosomal cathepsin L activity, and apoptosis.
- Tools used to test the mechanism: bafilomycin A1 to block the final degradation step of mitophagy, Mdivi-1 to inhibit Drp1-driven fission, torin 1 to inhibit mTOR, the antioxidant N-acetyl-cysteine to scavenge reactive oxygen species, and inhibitors of p38 and JNK.
Results
- Superoxide from mitochondria rose and mitochondrial membrane potential fell with nicotine.
- Mitophagic flux through PINK1/Parkin was impaired, and lysosomal cathepsin L activity dropped.
- Fission increased and fusion was suppressed, and the excess fission led to apoptosis.
- Mdivi-1 alleviated the apoptosis.
- Torin 1 restored cathepsin L activity, reversed the nicotine-driven mTOR activation and mitophagy impairment, lowered mitochondria-derived superoxide, and blunted both fission and apoptosis.
- N-acetyl-cysteine and the p38 and JNK inhibitors also relieved the mitophagy impairment and produced effects on mitochondria similar to torin 1, which implicates a ROS/p38/JNK signaling pathway.
How Nicotine Hurts Mitochondria
Simple model: nicotine raises reactive oxygen species in the cardiomyocyte, ROS signaling through p38 and JNK weakens lysosomal cathepsin L, weak cathepsin L stalls mitophagic flux so damaged mitochondria are not cleared, the stalled flux pushes the network toward Drp1-driven fission and away from mitofusin-driven fusion, and the resulting excessive fragmentation triggers apoptosis. Remove the ROS or restore cathepsin L, as torin 1 did, and the chain breaks.
Practical Health Moves While Quitting Nicotine
- Exercise most days: brisk movement supports mitochondrial biogenesis.
- Sleep a full night: sleep loss increases oxidative stress and cravings.
- Nutrition for mitochondria: fatty fish, olive oil, leafy greens, berries, nuts, legumes.
- Focus without nicotine: timed deep-work blocks, slow breathing, morning sunlight, and a cutoff for caffeine in the afternoon.
Related Studies and Research
Nicotine and Endothelial Function: Reviews how nicotine affects vascular tone and oxidative stress.
Nicotine and Cognition: Meta-Analysis: Summarizes findings on nicotine’s impact on memory and attention.
Nicotine Patch in MCI Cognitive Trial: Examines whether nicotine aids in cognitive preservation in aging brains.
Podcast: Why This Neurosurgeon Will Never Use Nicotine: A breakdown of nicotine’s true effects on the body and brain.
Frequently Asked Questions
Does this study show nicotine damages the human heart?
Not directly. This was cultured rat heart muscle cells. It describes a mechanism, how nicotine drives mitochondrial fragmentation and apoptosis in cardiomyocytes, and it fits with nicotine’s known status as a cardiovascular risk factor. It is not evidence collected from patients.
Is vaping different from smoking here?
The authors note that the nicotine at issue is present in traditional cigarettes, hookahs, and e-cigarettes alike. The damage in this experiment came from nicotine applied to cells, with no smoke involved.
If I quit, can mitochondria recover?
This study did not follow people after quitting, so I cannot answer from it. What it does show is that the injury runs through reactive oxygen species and a stalled recycling pathway.
What supplements help mitochondria while quitting?
Food and habits matter most. The antioxidant used in this study, N-acetyl-cysteine, was a laboratory tool applied to cells, not a tested treatment for smokers. If you use supplements, discuss them with your clinician.
Conclusion
In rat heart muscle cells, nicotine raised mitochondrial superoxide, blocked PINK1/Parkin mitophagy by weakening cathepsin L through ROS, p38, and JNK signaling, and drove Drp1-mediated fission that ended in apoptosis. That is a mechanism, not a patient outcome, but it is a coherent one, and it argues for the same practical move: plan your exit from nicotine and support your mitochondria with sleep, exercise, and a nutrient-dense diet.
