Mechanism of Action

Asthma: Dreams of Anticholinergics

Adam J. Brown, MD — Sat, 16 May 2026 13:10:41 +0000

Asthma treatment wasn’t always built around inhalers. It once came from poisonous plants, smoke, and a mysterious dream. In this episode, we explore the strange history of anticholinergics, tracing the path from Jimsonweed and belladonna to atropine, acetylcholine, and Otto Loewi’s discovery of “Vagusstoff.” We follow how Loewi’s frog-heart experiment helped prove that nerves communicate through chemical messengers, and how Henry Dale’s work connected those discoveries to the vagus nerve and airway constriction. We examine why early plant-based asthma remedies could open the airways while also causing dangerous side effects, and how that understanding eventually led to modern anticholinergic therapy. This episode reveals how a dream, a frog heart, and a toxic smoke helped shape the pharmacology of asthma.

Chapters

(00:00:00) - The Dream That Changed Asthma Medicine
(00:00:58) - Types of Neurotransmitters
(00:02:41) - Dr. Otto Loewi’s Has a Dream
(00:04:22) - Smoking Plants for Asthma
(00:06:02) - Jimsonweed
(00:08:27) - Belladonna
(00:11:36) - Atropine Isolated
(00:13:26) - The Autonomic Nervous System
(00:14:44) - The Vagus Nerve
(00:17:36) - The Frog Heart Experiment
(00:18:54) - Vagusstoff Becomes Acetylcholine
(00:19:42) - Henry Dale and Anticholinergic
(00:21:49) - The Problem With Inhaled Atropine
(00:22:15) - Modern Anticholinergic Therapy
(00:23:56) - Outro

Asthma: From the Greeks to Albuterol How Science Unraveled the Airways

Adam J. Brown, MD — Sat, 11 Apr 2026 18:00:00 +0000

Asthma wasn’t always a diagnosis—it was once just a word for breathlessness. In this episode, we explore how asthma evolved from a nonspecific symptom into a defined disease of the small airways. From early descriptions in Greek medicine to the pathologic insights of Morgagni and the mechanistic thinking of Henry Hyde Salter, we follow the key discoveries that shaped our understanding of asthma. We examine how airway inflammation, bronchospasm, mucus plugging, and allergic responses were gradually identified as central features of the disease. This episode sets the stage for understanding the modern pathophysiology of asthma and the therapies that followed.

Chapters

(00:00:00) - Opening: Episode Setup
(00:01:29) - Story: A Sickly Child in the 1800s
(00:05:57) - What Is Asthma? (Modern Definition)
(00:06:40) - Asthma Symptoms & Triggers
(00:08:55) - Origins of the Word “Asthma”
(00:09:55) - Muscle Contractions: Early Clinical Observations
(00:13:39) - Allergy & Inflammation: 20th Century Shift
(00:14:46) - Animal Models of Asthma
(00:18:51) - Human Trials with Histamine
(00:20:21) - Closing

Breaking the RAAS Cycle: ACE Inhibition in Heart and Kidney Disease

Adam J. Brown, MD — Thu, 12 Mar 2026 19:10:26 +0000

From the discovery of a mysterious blood-pressure–lowering effect in the venom of a Brazilian pit viper to the development of the first ACE inhibitor, we trace how scientists transformed a deadly toxin into lifesaving medicine. We follow the work that identified bradykinin-potentiating peptides in snake venom and revealed that angiotensin-converting enzyme could be blocked—leading to the creation of captopril and later drugs such as enalapril and lisinopril. Along the way, landmark experiments and clinical trials showed that ACE inhibitors do far more than lower blood pressure, reshaping the treatment of heart failure and chronic kidney disease by targeting maladaptive activation of the renin–angiotensin–aldosterone system.

Chapters

(00:00:00) - ACE Inhibitor Story Continues: Shutting off RAAS
(00:01:00) - Recap: The RAAS Refresher
(00:02:36) - Venom Mystery : Why Pit Viper Bites Cause Hypotension
(00:05:02) - Venom and the ACE Connection: John Vane's Lab
(00:06:20) - Interview With a Pit Viper: Snake’s Take on Pharma
(00:09:18) - Venom Into Medicine: Turning Raw Venom into a Drug
(00:10:04) - Captopril: The First ACE Inhibitor
(00:11:04) - Better ACE Inhibitors: Captopril to Enalapril to Lisinopril
(00:12:35) - Maladaptive RAAS Activation: Heart Failure Activates Renin
(00:19:36) - Maladaptive RAAS Activation: Kidney Failure Activates Renin
(00:24:24) - Episode Conclusion: ACE Inhibitors Transform Cardiorenal Medicine

ACE Inhibitors, RAAS Physiology, and Snake Venom: Renin, Angiotensin, and Kidney Blood Pressure Control

Adam J. Brown, MD — Wed, 11 Feb 2026 22:27:38 +0000

From grinding up kidneys and injecting the extracts into animals to the famous Goldblatt clamp experiment, we trace decades of bold science that uncovered the body's most elaborate blood pressure system piece by piece. In part one of a two-part story, we follow the kidney's rise from simple filter to master regulator — through the discovery of renin, the bitter 17-year naming rivalry between Buenos Aires and Cleveland, and the identification of the enzyme that activates it all. Along the way, we encounter a Brazilian pit viper whose venom holds a molecular clue to one of modern medicine's greatest breakthroughs.

Chapters

(00:00:00) - ACE Inhibitors: A Two-Part Story Begins
(00:01:00) - Catching Up: Hypertension, Early Treatments, and Accidental Drugs
(00:02:35) - What Is an ACE Inhibitor?
(00:03:27) - Step-by-Step RAAS: Renin → Angiotensin → Aldosterone
(00:05:43) - Enter the Brazilian Pit Viper: Venom and Hypotension
(00:07:45) - Dr. Richard Bright and the Kidney–Heart Connection
(00:09:13) - Tigerstedt and the Discovery of Renin
(00:10:27) - Wild Inspiration: Brown-Séquard’s Influence
(00:11:36) - Rabbit Kidney Extracts and a Pressor Substance
(00:13:52) - Goldblatt’s Clip: Renal Ischemia Causes Hypertension
(00:16:45) - Buenos Aires Group: What Is the Kidney Secreting?
(00:19:00) - Hypertensin vs. Angiotonin: Two Names, One Substance
(00:22:09) - Dr. Skeggs: Angiotensin I vs II
(00:23:30) - Sodium Chloride and the Hint of ACE
(00:24:05) - Recap and Tease for Part Two

Mercury, the First Antibiotic, and the Birth of Thiazide Diuretics

Adam J. Brown, MD — Tue, 13 Jan 2026 00:16:00 +0000

From mercury injections in early syphilis and heart failure patients to the discovery of carbonic anhydrase and the rise of sulfa drugs, we follow how physicians first learned to manipulate fluid balance. We also explore the development of acetazolamide and the eventual breakthrough of thiazide diuretics—revealing how observation and experimentation reshaped the treatment of heart failure and high blood pressure.

Chapters

(00:01:18) - What are diuretics?
(00:02:28) - Mercury for congenital syphilis & surprise diuresis
(00:08:46) - Mercury’s problems & the need for safer diuretics
(00:10:26) - Sulfa drugs & penicillin’s first patient
(00:12:24) - Sulfanilamide, acidosis, and the first kidney clues
(00:15:01) - Discovery of carbonic anhydrase and its significance
(00:17:36) - Designing better carbonic anhydrase inhibitors (Acetazolamide)
(00:19:55) - Chlorthiazide and the thiazide era
(00:21:26) - Wrap-up

Muscle Poisons, Malaria, and Hydralazine Roots: The First Pharmacological Options For Hypertension

Adam J. Brown, MD — Sat, 20 Dec 2025 16:09:20 +0000

Dive into the first real medications used to treat dangerously high blood pressure. From muscle poisons and anti-malarials to a plant root used for centuries, we trace how hydralazine and reserpine emerged as early antihypertensive therapies. We also explore the landmark VA Cooperative Study, which proved that lowering blood pressure could prevent strokes, heart failure, and kidney damage—and began changing modern medicine.

Chapters

(00:00:00) - Introduction: Hypertension Pharmacological Options
(00:02:48) - Sodium Thiocyanate: The First BP-Lowering Medication
(00:04:58) - Landmark Study: VA Cooperative
(00:08:12) - Anti-Malarials: The Accidental Hypertension Treatement
(00:10:29) - Pentaquine: The First Proof
(00:13:42) - Hydralazine: An Anti-Malarial That Became a Blood Pressure Drug
(00:15:04) - Reserpine: The Plant That Lowered Blood Pressure
(00:19:09) - Turning Point: The Beginning of Modern Hypertension Care
(00:22:03) - Outro: What Comes Next

Blood, Salt and Sympathectomies: Early Interventions and Blood Pressure Management

Adam J. Brown, MD — Mon, 01 Dec 2025 22:53:00 +0000

Before thiazides and ACE inhibitors, clinicians relied on bleeding, low-salt diets, metabolic experiments, and even nerve-cutting surgeries to manage dangerous blood pressure. This episode explains how these early interventions—and key discoveries about volume, salt, and baroreceptors—shaped our understanding of hypertension and paved the way for pharmacologic breakthroughs.

Chapters

(00:00:00) - Introduction: Early Battles With Blood Pressure
(00:02:08) - Bloodletting: The First “Therapy”
(00:04:53) - Patient Story: “Mom, I Don’t Want to Die”
(00:06:59) - Sponsor Break: Dr. Clay’s Drainage Kit
(00:08:43) - Enter Salt: The Oldest Dietary Culprit
(00:14:05) - Diets & The Rise of the “Rice Houses”
(00:21:09) - Baroreceptors: The Nervous System’s Pressure Sensors
(00:25:11) - Sympathectomies: Cutting Nerves to Cut Pressure
(00:26:41) - Recap & What Comes Next

Animal Cruelty, Obliterating Arteries, and Insurance Actuaries: How Medicine Recognized the Dangers of Hypertension

Adam J. Brown, MD — Fri, 28 Nov 2025 23:45:00 +0000

We trace the origins of how medicine first understood and measured blood pressure. From early fluid-pressure experiments and invasive animal studies to the invention of the modern blood-pressure cuff, we follow the slow realization that chronically elevated blood pressure is dangerous. We also explore the long-standing debate surrounding "essential hypertension" and how research—from Janeway's observations to insurance-company data and the Framingham Study—ultimately shifted medical practice toward active treatment.

Chapters

(00:00:00) - Intro: History of Blood Pressure
(00:01:35) - What is Blood Pressure
(00:03:53) - Normal vs High Blood Pressure
(00:04:48) - Histories View of Hypertension
(00:07:35) - The Origin of Blood Pressure Measurement
(00:09:12) - Stephen Hales & Animal Experiments
(00:12:44) - Measurement Devices
(00:15:55) - Early Clues of Danger: Kidneys, Hearts
(00:19:25) - What Famous Clinicians Believed
(00:24:31) - Hypertensions Dangers Emerge
(00:25:27) - Insurance Actuaries Enter the Scene
(00:27:20) - The Framingham Heart Study
(00:27:52) - Closing

Trailer: Introducing Mechanism of Action

Adam J. Brown, MD — Sat, 09 Aug 2025 10:22:44 +0000

Hosted by Dr. Adam Brown, a rheumatologist with a deep passion for medical history, Mechanism of Action invites you on a journey through the hidden chapters of modern medicine. From the first whispers of mysterious illnesses to the lab discoveries that revolutionized treatment, this show uncovers the fascinating stories behind the drugs we depend on.